Newton's laws

1. Introduction

2. Force

3. Basic types of forces



ID is: 3691 Seed is: 6921

Comparing types of friction

Objects can experience different forms of the frictional force: static friction, maximum static friction, and kinetic friction.

In the question below there is a list of four facts about each of these forces. Each list is missing two pieces of information. Complete the lists by selecting the correct choices.

Answer:

Static friction (fs)

  • experienced by a stationary object
  • have a formula
  • depend on the roughness of the surfaces in contact
  • does depend on other forces parallel to the surface

Maximum static friction (fsmax)

  • experienced by a stationary object
  • have a formula
  • depend on the roughness of the surfaces in contact
  • does not depend on other forces parallel to the surface

Kinetic friction (fk)

  • experienced by a moving object
  • have a formula
  • depend on the roughness of the surfaces in contact
  • does not depend on other forces parallel to the surface

ID is: 3691 Seed is: 2924

Comparing types of friction

Objects can experience different forms of the frictional force: static friction, maximum static friction, and kinetic friction.

In the question below there is a list of four facts about each of these forces. Each list is missing two pieces of information. Complete the lists by selecting the correct choices.

Answer:

Static friction (fs)

  • experienced by a stationary object
  • have a formula
  • depend on the roughness of the surfaces in contact
  • does depend on other forces parallel to the surface

Maximum static friction (fsmax)

  • experienced by a stationary object
  • have a formula
  • depend on the roughness of the surfaces in contact
  • does not depend on other forces parallel to the surface

Kinetic friction (fk)

  • experienced by a moving object
  • have a formula
  • depend on the roughness of the surfaces in contact
  • does not depend on other forces parallel to the surface


ID is: 3325 Seed is: 1696

Definition: The normal force

Define the term normal force using the dropdown menus below.

Answer:

The normal force (N or FN) is the force which a exerts on an object with which it is , and which points the .


ID is: 3325 Seed is: 3151

Definition: The normal force

Define the term normal force using the dropdown menus below.

Answer:

The normal force (N or FN) is the force which a exerts on an object with which it is , and which points the .



ID is: 3324 Seed is: 8570

Definition: tension

Define tension using the dropdown menus below.

Answer:

Tension is the magnitude of the that is exerted by of a rope, wire, or other similar object. The is directed the rope and the magnitude is the rope.


ID is: 3324 Seed is: 1317

Definition: tension

Define tension using the dropdown menus below.

Answer:

Tension is the magnitude of the that is exerted by of a rope, wire, or other similar object. The is directed the rope and the magnitude is the rope.



ID is: 3676 Seed is: 295

Factors affecting kinetic friction

An object is sliding down a rough slope.

As the object slides, it experiences the kinetic frictional force (fk). Various properties of the object and the slope will affect this force, but some will not.

  1. For each property below, decide whether it does or does not affect the magnitude of the kinetic frictional force experienced by the object.

    Answer:

    The magnitude of the kinetic frictional force is affected by:

    • the material the object is made from:
    • the speed of object:
    • the material the slope is made from:
  2. The slope is covered with a thin layer of rougher material. Will the magnitude of the kinetic frictional force increase, decrease, or remain the same?

    Select a reason for your answer from the table of reasons given below. Assume that all other properties of the object and the slope remain the same.

    A The object and the slope will be pushing into each other less and so the normal force on the object will decrease.
    B It will be easier for the object to slide because the coefficient of friction between the object and the slope will decrease.
    C It will be harder for the object to slide because the coefficient of friction between the object and the slope will increase.
    D The object and the slope will be pushing into each other more and so the normal force on the object will increase.
    Answer:

    If the slope is covered with a thin layer of rougher material, the magnitude of the kinetic frictional force would .

    This is because of Reason .


ID is: 3676 Seed is: 402

Factors affecting kinetic friction

An object is sliding down a rough slope.

As the object slides, it experiences the kinetic frictional force (fk). Various properties of the object and the slope will affect this force, but some will not.

  1. For each property below, decide whether it does or does not affect the magnitude of the kinetic frictional force experienced by the object.

    Answer:

    The magnitude of the kinetic frictional force is affected by:

    • the angle of inclination of the slope:
    • the mass of the object:
    • the contact surface area between the object and the slope:
  2. The angle that the slope forms with the horizontal is decreased. Will the magnitude of the kinetic frictional force increase, decrease, or remain the same?

    Select a reason for your answer from the table of reasons given below. Assume that all other properties of the object and the slope remain the same.

    A It will be harder for the object to slide because the coefficient of friction between the object and the slope will increase.
    B The object and the slope will be pushing into each other less and so the normal force on the object will decrease.
    C The object and the slope will be pushing into each other more and so the normal force on the object will increase.
    D It will be easier for the object to slide because the coefficient of friction between the object and the slope will decrease.
    Answer:

    If the angle that the slope forms with the horizontal is decreased, the magnitude of the kinetic frictional force would .

    This is because of Reason .



ID is: 3661 Seed is: 2572

Understanding fsmax=μsFN

The relationship fsmax=μsFN is an important equation in mechanics.

  1. What does the symbol fsmax represent?

    Answer:

    The symbol fsmax represents the .

  2. What is the SI unit in which we measure FN?

    Answer:

    The SI unit in which we measure FN is .


ID is: 3661 Seed is: 6308

Understanding fk=μkFN

The relationship fk=μkFN is an important equation in mechanics.

  1. What does the symbol μk represent?

    Answer:

    The symbol μk represents the .

  2. What is the SI unit in which we measure FN?

    Answer:

    The SI unit in which we measure FN is .



ID is: 3326 Seed is: 1368

Definitions: Coefficients of friction

Define the coefficient of static friction using the dropdown menus below.

Answer:

The coefficient of static friction (μs) is defined as the the and experienced by an object in contact with a surface.

It is which means it . It depends on .


ID is: 3326 Seed is: 2184

Definitions: Coefficients of friction

Define the coefficient of static friction using the dropdown menus below.

Answer:

The coefficient of static friction (μs) is defined as the the and experienced by an object in contact with a surface.

It is which means it . It depends on .



ID is: 3328 Seed is: 6526

Definitions: Frictional forces

There are several different types of frictional force in mechanics.

Define frictional force using the dropdown menus below.

Answer:

The frictional force (f or Ff) is the force that the relative motion between a object and a surface. This force acts the surface.


ID is: 3328 Seed is: 2897

Definitions: Frictional forces

There are several different types of frictional force in mechanics.

Define frictional force using the dropdown menus below.

Answer:

The frictional force (f or Ff) is the force that the relative motion between a object and a surface. This force acts the surface.



ID is: 3694 Seed is: 8295

What type of friction is acting?

Luyanda is sitting at a desk and stands up quickly. As she stands, she tilts the desk and a book almost slips off the desk. If she had tilted the desk any further, the book would have slipped off.

What specific type of frictional force is involved in the above scenario?

Answer:

There is involved in the scenario.


ID is: 3694 Seed is: 5435

What type of friction is acting?

A plain wooden chair lies abandoned in a flat school corridor.

What specific type of frictional force is involved in the above scenario?

Answer:

There is involved in the scenario.



ID is: 3454 Seed is: 8584

Working out the normal force

Amadi is investigating the motion of a crate as it slides to the left along a rough horizontal surface.

The following force diagram shows all the forces exerted on the crate except for the normal force.

Which one of the following force diagrams shows the correct size and direction of the normal force FN?

A

B

C

D

Answer:

The normal force is correctly shown in diagram:


ID is: 3454 Seed is: 4586

Working out the normal force

Chichi is investigating the motion of a box as it slides up a rough wooden ramp.

The following free-body diagram shows all the forces exerted on the box except for the normal force.

Which one of the following free-body diagrams shows the correct size and direction of the normal force FN?

A

B

C

D

Answer:

The normal force is correctly shown in diagram:



ID is: 3456 Seed is: 4890

The normal force on a slope

Mzwandile is investigating the motion of a box as it slides up a rough wooden ramp.

The following force diagram shows all the forces exerted on the box.

Mzwandile now increases α, the angle of the ramp.

Will the magnitude of the normal force experienced by the box increase, decrease, or remain the same? Give a reason for your answer.

Answer:

The magnitude of the normal force will .

This is because increasing the angle of the ramp will the magnitude of the normal force.


ID is: 3456 Seed is: 8794

The normal force on a slope

Bridget is investigating the motion of an object as it slides up a rough wooden ramp.

The following free-body diagram shows all the forces exerted on the object.

Bridget now decreases α, the angle of the ramp.

Will the magnitude of the normal force experienced by the object increase, decrease, or remain the same? Give a reason for your answer.

Answer:

The magnitude of the normal force will .

This is because decreasing the angle of the ramp will the magnitude of the normal force.



ID is: 3458 Seed is: 1997

The normal force on a horizontal surface

Kate is investigating the motion of an object as it slides to the left along a rough horizontal surface.

The following free-body diagram shows all the forces exerted on the object.

Kate now pulls on the object with a force that is angled out of the surface to the left.

Will the magnitude of the normal force increase, decrease, or remain the same? Give a reason for your answer.

Answer:

The magnitude of the normal force will .

This is because pulling on the object with a force that is angled out of the surface will the magnitude of the force the object exerts perpendicularly into the surface.


ID is: 3458 Seed is: 5469

The normal force on a horizontal surface

Thato is investigating the motion of an object as it slides to the left along a rough horizontal surface.

The following force diagram shows all the forces exerted on the object.

Thato now pushes on the object with a force that is angled into the surface to the left.

Will the magnitude of the normal force increase, decrease, or remain the same? Give a reason for your answer.

Answer:

The magnitude of the normal force will .

This is because pushing on the object with a force that is angled into the surface will the magnitude of the force the object exerts perpendicularly into the surface.



ID is: 3677 Seed is: 5072

Factors affecting kinetic friction

An object is sliding along a rough horizontal surface.

As the object slides, it experiences the kinetic frictional force (fk). Various properties of the object and the surface will affect this force, but some will not.

  1. For each property below, decide whether it does or does not affect the magnitude of the kinetic frictional force experienced by the object.

    Answer:

    The magnitude of the kinetic frictional force is affected by:

    • the speed of object:
    • the material the surface is made from:
    • the contact surface area between the object and the surface:
  2. The surface is covered with a thin layer of smoother material. Will the magnitude of the kinetic frictional force increase, decrease, or remain the same?

    Select a reason for your answer from the table of reasons given below. Assume that all other properties of the object and the horizontal surface remain the same.

    A It will be easier for the object to slide because the coefficient of friction between the object and the surface will decrease.
    B The object and surface will be pushing into each other more and so the normal force on the object will increase.
    C The object and surface will be pushing into each other less and so the normal force on the object will decrease.
    D It will be harder for the object to slide because the coefficient of friction between the object and the surface will increase.
    Answer:

    If the surface is covered with a thin layer of smoother material, the magnitude of the kinetic frictional force will .

    This is because of Reason .


ID is: 3677 Seed is: 4375

Factors affecting kinetic friction

An object is sliding along a rough horizontal surface.

As the object slides, it experiences the kinetic frictional force (fk). Various properties of the object and the surface will affect this force, but some will not.

  1. For each property below, decide whether it does or does not affect the magnitude of the kinetic frictional force experienced by the object.

    Answer:

    The magnitude of the kinetic frictional force is affected by:

    • the material the surface is made from:
    • the material the object is made from:
    • the contact surface area between the object and the surface:
  2. The surface is covered with a thin layer of rougher material. Will the magnitude of the kinetic frictional force increase, decrease, or remain the same?

    Select a reason for your answer from the table of reasons given below. Assume that all other properties of the object and the horizontal surface remain the same.

    A It will be harder for the object to slide because the coefficient of friction between the object and the surface will increase.
    B The object and surface will be pushing into each other more and so the normal force on the object will increase.
    C The object and surface will be pushing into each other less and so the normal force on the object will decrease.
    D It will be easier for the object to slide because the coefficient of friction between the object and the surface will decrease.
    Answer:

    If the surface is covered with a thin layer of rougher material, the magnitude of the kinetic frictional force will .

    This is because of Reason .



ID is: 3477 Seed is: 3227

Identifying the normal force

The following free-body diagram shows five forces acting on an object that is in contact with a wall.

Which one of the forces represents the normal force?

Answer:

The normal force is represented by:


ID is: 3477 Seed is: 8763

Identifying the normal force

The following free-body diagram shows five forces acting on an object that is in contact with a horizontal surface.

Which one of the forces represents the normal force?

Answer:

The normal force is represented by:



ID is: 3599 Seed is: 8090

The relationship between FN, μk, and fk

The normal force (FN), the coefficient of kinetic friction (μk), and the kinetic frictional force (fk) are three important quantities in mechanics.

Which one of the following equations correctly represents the relationship between these quantities?

A μk=fkFN
B μk=FNfk
C μk=FNfk
Answer:

The correct equation is:


ID is: 3599 Seed is: 4513

The relationship between fk, FN, and μk

The kinetic frictional force (fk), the normal force (FN), and the coefficient of kinetic friction (μk) are three important quantities in mechanics.

Which one of the following equations correctly represents the relationship between these quantities?

A FN=μkfk
B FN=fkμk
C FN=fkμk
Answer:

The correct equation is:

3. Newton's laws

4. Frictional forces



ID is: 3745 Seed is: 3803

Frictional forces

A book is at rest on the surface of a rough plastic desk. Chike pulls on the book and the book slides along the surface. The value of maximum static friction for the book and the table is 11 N. Below is the force diagram showing all forces acting on the book.

  1. After Chike starts pulling on the book, what type of frictional force does the book experience?
  2. What can we say about the magnitude of the frictional force exerted on the book?
Answer:
  1. The object experiences friction.
  2. The magnitude of the frictional force is N.

ID is: 3745 Seed is: 486

Frictional forces

A box is at rest on the surface of a rough wooden desk. Atinuke pulls on the box, but the box will not shift from its position. Atinuke can tell that even if she pulled harder, it would still not move. The value of maximum static friction for the box and the table is 80 N. Below is the force diagram showing all forces acting on the box.

  1. After Atinuke starts pulling on the box, what type of frictional force does the box experience?
  2. What can we say about the magnitude of the frictional force exerted on the box?
Answer:
  1. The object experiences friction.
  2. The magnitude of the frictional force is N.


ID is: 1430 Seed is: 3853

Working with the coefficient of static friction

A box is at rest on a rough surface. It experiences a normal force of magnitude 206 N. The coefficient of static friction between the surface and the box (μs) is 0,52.

What is the magnitude of the maximum static frictional force (fsmax)?

INSTRUCTION: Round your answer to two decimal places.
Answer:

fsmax= N

one-of
type(numeric.abserror(0.01))

ID is: 1430 Seed is: 140

Working with the coefficient of static friction

A box is at rest on a rough surface. It experiences a normal force of magnitude 185 N. The magnitude of the maximum static frictional force (fsmax) is 66,6 N.

What is the coefficient of static friction (μs)?

INSTRUCTION: Round your answer to two decimal places.
Answer:

μs=

one-of
type(numeric.abserror(0.01))


ID is: 3687 Seed is: 4327

The story of the friction graph

Bukelwa applies a pushing force to a bookshelf that is initially at rest on a rough horizontal surface. The force that Bukelwa applies is parallel to the surface.

The following is a graph of the magnitude of the frictional force (f) experienced by the bookshelf plotted against the magnitude of the applied pushing force (Fpush).

Graphs tell stories! The table below tells the story of the graph in four parts, but in the wrong order. Match each part of the story with a label from the graph (A - D).

Answer:
When Bukelwa pushes with a force greater than maximum static friction, the bookshelf starts to move and it will experience a kinetic frictional force. The magnitude of the kinetic frictional force is less than the maximum static frictional force. It is independent of the size of the pushing force.
Before Bukelwa starts pushing on the stationary bookshelf, it experiences zero frictional force.
Once Bukelwa starts to push on the stationary bookshelf it experiences a static frictional force. As she increases the magnitude of the force with which she pushes, the bookshelf remains stationary, and the magnitude of the static frictional force increases.
The magnitude of the static frictional force reaches its largest possible value, called maximum static friction. When the magnitude of the pushing force is equal to maximum static friction, the bookshelf is stationary, but just about to start moving.

ID is: 3687 Seed is: 7748

The story of the friction graph

Emmanuel applies a pushing force to a bookshelf that is initially at rest on a rough horizontal surface. The force that Emmanuel applies is parallel to the surface.

The following is a graph of the magnitude of the frictional force (f) experienced by the bookshelf plotted against the magnitude of the applied pushing force (Fpush).

Graphs tell stories! The table below tells the story of the graph in four parts, but in the wrong order. Match each part of the story with a label from the graph (E - H).

Answer:
When Emmanuel pushes with a force greater than maximum static friction, the bookshelf starts to move and it will experience a kinetic frictional force. The magnitude of the kinetic frictional force is less than the maximum static frictional force. It is independent of the size of the pushing force.
The magnitude of the static frictional force reaches its largest possible value, called maximum static friction. When the magnitude of the pushing force is equal to maximum static friction, the bookshelf is stationary, but just about to start moving.
Once Emmanuel starts to push on the stationary bookshelf it experiences a static frictional force. As he increases the magnitude of the force with which he pushes, the bookshelf remains stationary, and the magnitude of the static frictional force increases.
Before Emmanuel starts pushing on the stationary bookshelf, it experiences zero frictional force.


ID is: 3455 Seed is: 4506

Friction and the normal force on a slope

Umar is investigating the motion of a crate as it slides up a rough wooden ramp.

The following free-body diagram shows all the forces exerted on the crate.

Umar now decreases α, the angle of the ramp.

Will the magnitude of the kinetic frictional force experienced by the crate increase, decrease, or remain the same? Give a reason for your answer.

Answer:

The magnitude of the kinetic frictional force will .

This is because decreasing the angle of the ramp will the magnitude of the normal force.


ID is: 3455 Seed is: 2612

Friction and the normal force on a slope

Gift is investigating the motion of a crate as it slides up a rough wooden ramp.

The following free-body diagram shows all the forces exerted on the crate.

Gift now increases α, the angle of the ramp.

Will the magnitude of the kinetic frictional force experienced by the crate increase, decrease, or remain the same? Give a reason for your answer.

Answer:

The magnitude of the kinetic frictional force will .

This is because increasing the angle of the ramp will the magnitude of the normal force.



ID is: 3693 Seed is: 3183

Factors affecting kinetic friction: horizontal

Two objects are sliding along two horizontal surfaces.

The only difference between the two objects is that Object A has a greater mass than Object B. The two horizontal surfaces are identical.

Which object will experience the smaller frictional force? Select a reason for your answer from the table below.

A lower mass...

A increases the normal force.
B decreases the normal force.
C increases the coefficient of kinetic friction.
D decreases the coefficient of kinetic friction.
E does not change either the normal force or the coefficient of kinetic friction.
Answer:

will experience the smaller frictional force. This is because a lower mass .


ID is: 3693 Seed is: 8278

Factors affecting kinetic friction: horizontal

Two objects are sliding along two horizontal surfaces.

The only difference between the two objects is that Object A is made from a smoother material than Object B. The two horizontal surfaces are identical.

Which object will experience the greater frictional force? Select a reason for your answer from the table below.

A greater roughness...

A increases the normal force.
B decreases the normal force.
C increases the coefficient of kinetic friction.
D decreases the coefficient of kinetic friction.
E does not change either the normal force or the coefficient of kinetic friction.
Answer:

will experience the greater frictional force. This is because a greater roughness .



ID is: 3690 Seed is: 4951

Maximum static friction and the critical angle of a slope

A wooden box is at rest on a rough slope which is inclined at an angle α to the horizontal.

  1. Write down expressions for the components of the gravitational force parallel and perpendicular to the slope.

    Use any of the following variables and trigonometric functions in your answers:

    mgαsincostan
    INSTRUCTIONS:
    • you can type a for the symbol α
    • put a space before trigonometric functions and brackets around the input angle e.g. type b tan(a) for btanα
    Answer:

    Fg,=

    Fg,=

    The component of the gravitational force has the same magnitude as the normal force, FN.

    one-of
    type(expression)
    one-of
    type(expression)
  2. The angle of the incline is gradually increased until the box is just about to start sliding down the slope. This angle, αc, is the critical angle of the slope. If this angle were any greater the component of the gravitational force parallel to the slope would exceed the maximum static frictional force and the box would start to slide down the slope.

    The following is a derivation of the relationship between the coefficient of static friction and the critical angle of the slope:

    μs=tan(αc)

    Study the derivation and answer the questions that follow.

    Derivation

    We will take "up the slope" as the positive direction:

    StepNo.fsmax+Fg,=Fnet,(1)fsmax+Fg,=0(2)μsFN+Fg,=0(3)μsFNmgsin(αc)=0(4)μsmgcos(αc)=mgsin(αc)(5)μscos(αc)=sin(αc)(6)μs=tan(αc)(7)

    The following seven statements are explanations of how one step of the derivation follows from the previous step. However, the explanations are in the incorrect order!

    A

    Use the definition of net force, Fnet, as the vector sum of all forces parallel to the slope.

    B

    Use Newton's second law for an object in static equilibrium

    Fnet=0
    C

    Substitute the normal force at the critical angle

    FN=mgcos(αc)

    and add mgsin(αc) to both sides of the equation.

    D

    Divide both sides by mg.

    E

    Substitute the component of the gravitational force parallel to the slope at the critical angle

    Fg,=mgsin(αc)
    F

    Use the formula for maximum static friction

    fsmax=μsFN
    G

    Divide both sides by cos(αc) and then use the trigonometric identity

    tan(αc)=sin(αc)cos(αc)

    Match each step in the derivation (1 to 7) with the correct explanation (A to G). Three of the steps have been done for you.

    Answer:
    1. fsmax+Fg,=Fnet,
      (Explanation A)
    2. fsmax+Fg,=0
    3. μsFN+Fg,=0
    4. μsFNmgsin(αc)=0
    5. μsmgcos(αc)=mgsin(αc)
    6. μscos(αc)=sin(αc)
      (Explanation D)
    7. μs=tan(αc)
      (Explanation G)

ID is: 3690 Seed is: 2614

Maximum static friction and the critical angle of a slope

A wooden block is at rest on a rough plank which is inclined at an angle α to the horizontal.

  1. Write down expressions for the components of the gravitational force parallel and perpendicular to the plank.

    Use any of the following variables and trigonometric functions in your answers:

    mgαsincostan
    INSTRUCTIONS:
    • you can type a for the symbol α
    • put a space before trigonometric functions and brackets around the input angle e.g. type b tan(a) for btanα
    Answer:

    Fg,=

    Fg,=

    The component of the gravitational force has the same magnitude as the normal force, FN.

    one-of
    type(expression)
    one-of
    type(expression)
  2. The angle of the incline is gradually increased until the block is just about to start sliding down the plank. This angle, αc, is the critical angle of the plank. If this angle were any greater the component of the gravitational force parallel to the plank would exceed the maximum static frictional force and the block would start to slide down the plank.

    The following is a derivation of the relationship between the coefficient of static friction and the critical angle of the plank:

    μs=tan(αc)

    Study the derivation and answer the questions that follow.

    Derivation

    We will take "up the plank" as the positive direction:

    StepNo.fsmax+Fg,=Fnet,(1)fsmax+Fg,=0(2)μsFN+Fg,=0(3)μsFNmgsin(αc)=0(4)μsmgcos(αc)=mgsin(αc)(5)μscos(αc)=sin(αc)(6)μs=tan(αc)(7)

    The following seven statements are explanations of how one step of the derivation follows from the previous step. However, the explanations are in the incorrect order!

    A

    Use the formula for maximum static friction

    fsmax=μsFN
    B

    Use the definition of net force, Fnet, as the vector sum of all forces parallel to the slope.

    C

    Substitute the normal force at the critical angle

    FN=mgcos(αc)

    and add mgsin(αc) to both sides of the equation.

    D

    Divide both sides by mg.

    E

    Substitute the component of the gravitational force parallel to the slope at the critical angle

    Fg,=mgsin(αc)
    F

    Divide both sides by cos(αc) and then use the trigonometric identity

    tan(αc)=sin(αc)cos(αc)
    G

    Use Newton's second law for an object in static equilibrium

    Fnet=0

    Match each step in the derivation (1 to 7) with the correct explanation (A to G). Three of the steps have been done for you.

    Answer:
    1. fsmax+Fg,=Fnet,
      (Explanation B)
    2. fsmax+Fg,=0
    3. μsFN+Fg,=0
      (Explanation A)
    4. μsFNmgsin(αc)=0
    5. μsmgcos(αc)=mgsin(αc)
    6. μscos(αc)=sin(αc)
      (Explanation D)
    7. μs=tan(αc)


ID is: 3549 Seed is: 5437

Friction and getting an object to start moving

Chiamaka applies a pushing force to a table that is initially at rest on a rough horizontal surface. The force that Chiamaka applies is parallel to the surface.

The paragraphs below describe how the frictional force changes as Chiamaka pushes harder. Use the drop-down menus below to complete the paragraphs.

Answer:

Before Chiamaka starts pushing on the stationary table, it experiences zero frictional force.

As she starts to push on the stationary table it experiences a static frictional force. As Chiamaka increases the magnitude of the force with which she pushes, the table remains stationary, and the magnitude of the frictional force until it reaches its biggest possible value, called friction.

When the magnitude of the pushing force is maximum static friction, the table is stationary, but just about to start moving. When Chiamaka pushes with a force greater than maximum static friction, the table starts to move and it will experience a frictional force. The magnitude of the kinetic frictional force is the maximum static frictional force.


ID is: 3549 Seed is: 757

Friction and getting an object to start moving

Chizoba applies a pulling force to a couch that is initially at rest on a rough horizontal surface. The force that Chizoba applies is parallel to the surface.

The paragraphs below describe how the frictional force changes as Chizoba pulls harder. Use the drop-down menus below to complete the paragraphs.

Answer:

Before Chizoba starts pulling on the stationary couch, it experiences zero frictional force.

As he starts to pull on the stationary couch it experiences a static frictional force. As Chizoba increases the magnitude of the force with which he pulls, the couch remains stationary, and the magnitude of the frictional force until it reaches its biggest possible value, called friction.

When the magnitude of the pulling force is maximum static friction, the couch is stationary, but just about to start moving. When Chizoba pulls with a force greater than maximum static friction, the couch and it will experience a kinetic frictional force. The magnitude of the kinetic frictional force is the maximum static frictional force.



ID is: 3343 Seed is: 571

Factors affecting kinetic friction

Two boxes are sliding down inclined planes.

The boxes are identical. The only difference between the two inclined planes is that Plane A is made from a rougher material than Plane B.

Which box will experience the smaller frictional force? Give a reason for your answer.

Answer:

will experience the smaller frictional force. This is because a lower .


ID is: 3343 Seed is: 4497

Factors affecting kinetic friction

Two boxes are sliding down inclined planes.

The only difference between the two boxes is that Box A has a greater mass than Box B. The two inclined planes are identical.

Which box will experience the greater frictional force? Give a reason for your answer.

Answer:

will experience the greater frictional force. This is because a greater .



ID is: 3457 Seed is: 7337

Friction and the normal force on a horizontal surface

Nthabiseng is investigating the motion of a box as it slides to the left along a rough horizontal surface.

The following force diagram shows all the forces exerted on the box.

Nthabiseng now pushes the box perpendicularly into the surface.

Will the magnitude of the kinetic frictional force experienced by the box increase, decrease, or remain the same? Give a reason for your answer.

Answer:

The magnitude of the kinetic frictional force will .

This is because pushing the box perpendicularly into the surface will the magnitude of the force the box exerts perpendicularly into the surface.


ID is: 3457 Seed is: 9447

Friction and the normal force on a horizontal surface

Gabisile is investigating the motion of a crate as it slides to the left along a rough horizontal surface.

The following force diagram shows all the forces exerted on the crate.

Gabisile now pushes the crate perpendicularly into the surface.

Will the magnitude of the kinetic frictional force experienced by the crate increase, decrease, or remain the same? Give a reason for your answer.

Answer:

The magnitude of the kinetic frictional force will .

This is because pushing the crate perpendicularly into the surface will the magnitude of the force the crate exerts perpendicularly into the surface.



ID is: 3689 Seed is: 607

Graphing friction

Marcel applies a pulling force to a table that is initially at rest on a rough horizontal surface. The force that Marcel applies is parallel to the surface.

The following is a graph of the magnitude of the frictional force experienced by the table plotted against the magnitude of the applied pulling force.

Match each of the descriptions in the table below with the correct label in the graph (P - T).

Answer:
the range of the applied force for which the table is moving
the frictional force has reached fsmax
the static frictional force matches the applied pulling force
the magnitude of the pulling force
the frictional force experienced by the table

ID is: 3689 Seed is: 6947

Graphing friction

Ajibike applies a pushing force to a couch that is initially at rest on a rough horizontal surface. The force that Ajibike applies is parallel to the surface.

The following is a graph of the magnitude of the frictional force experienced by the couch plotted against the magnitude of the applied pushing force.

Match each of the descriptions in the table below with the correct label in the graph (D - H).

Answer:
the range of the applied force for which the couch is stationary
the kinetic frictional force is independent of the applied pushing force
the magnitude of the frictional force
the magnitude of the pushing force
the frictional force has reached fsmax


ID is: 4565 Seed is: 3679

How the normal force affects friction

Adapted from DBE Nov 2015 Grade 11, P1, Q3
Physical constants · Physics formulas

A block of mass m is placed on a rough horizontal surface. A constant force (F) pushes the block, but the block remains at rest as shown in the diagram below. The coefficient of static friction between the block and the surface is μs. If the magnitude of the applied force were any larger, the block would begin to move.

The force is changed to one of the same magnitude but in the direction shown in the diagram below. The block and rough surface stay the same.

Describe what will happen to the block. Give a reason for your answer.

Answer:

The block will ...

This is because the normal force ...


ID is: 4565 Seed is: 7648

How the normal force affects friction

Adapted from DBE Nov 2015 Grade 11, P1, Q3
Physical constants · Physics formulas

A block of mass m is placed on a rough horizontal surface. A constant force (F) pushes the block, but the block remains at rest as shown in the diagram below. The coefficient of static friction between the block and the surface is μs. If the magnitude of the applied force were any larger, the block would begin to move.

The force is changed to one of the same magnitude but in the direction shown in the diagram below. The block and rough surface stay the same.

Describe what will happen to the block. Give a reason for your answer.

Answer:

The block will ...

This is because the normal force ...



ID is: 3692 Seed is: 9954

MCQ: Factors affecting kinetic friction

Two boxes are sliding down two slopes.

Box A on Slope A

Box B on Slope B

There are only two differences.

  1. Slope A is inclined at a smaller angle to the horizontal than Slope B.
  2. Slope A is made from a rougher material than Slope B.

Which box will experience the smaller kinetic frictional force?

A Box A
B Box B
C Neither box
D Impossible to tell
Answer:

The correct option is:


ID is: 3692 Seed is: 6394

MCQ: Factors affecting kinetic friction

Two boxes are sliding down two slopes.

Box A on Slope A

Box B on Slope B

There are only two differences.

  1. Box A is lower on the slope than Box B.
  2. Box A has a smaller contact area with the slope than Box B.

Which box will experience the greater kinetic frictional force?

A Box A
B Box B
C Neither box
D Impossible to tell
Answer:

The correct option is:



ID is: 3688 Seed is: 1606

The friction graph and force diagrams

Chijindum applies a pulling force to a crate that is initially at rest on a rough horizontal surface. The force that Chijindum applies is parallel to the surface.

Chijindum gradually increases the magnitude of the pulling force.

The following is a graph of the magnitude of the frictional force (f) experienced by the crate plotted against the magnitude of the applied pulling force (Fpull).

The graph shows the relationship between the two parallel forces experienced by the box. The force diagram below is also a way of representing the relationship between the parallel forces at a given point.

Match the force diagram with a label from the graph (P - S).

Answer:

The given force diagram matches .


ID is: 3688 Seed is: 1057

The friction graph and force diagrams

Chibuike applies a pulling force to a bookshelf that is initially at rest on a rough horizontal surface. The force that Chibuike applies is parallel to the surface.

Chibuike gradually increases the magnitude of the pulling force.

The following is a graph of the magnitude of the frictional force (f) experienced by the bookshelf plotted against the magnitude of the applied pulling force (Fpull).

The graph shows the relationship between the two parallel forces experienced by the box. The force diagram below is also a way of representing the relationship between the parallel forces at a given point.

Match the force diagram with a label from the graph (W - Z).

Answer:

The given force diagram matches .



ID is: 1550 Seed is: 4630

Coefficients of friction

A block of wood weighing 32 N is placed on a rough, flat surface and a rope is tied to it. The tension in the rope can be increased to 16,1 N before the block starts to slide. A force of 12,6 N will keep the block moving at constant speed once it has been set in motion. Determine the coefficients of static and kinetic friction.

INSTRUCTION: Round your answers to two decimal places.
Answer:

μs=
μk=

one-of
type(numeric.abserror(0.01))
one-of
type(numeric.abserror(0.01))

ID is: 1550 Seed is: 4323

Coefficients of friction

A toy car weighing 80 N is placed on a rough, flat surface and a rope is tied to it. The tension in the rope can be increased to 43,2 N before the car starts to slide. A force of 30,3 N will keep the car moving at constant speed once it has been set in motion. Determine the coefficients of static and kinetic friction.

INSTRUCTION: Round your answers to two decimal places.
Answer:

μs=
μk=

one-of
type(numeric.abserror(0.01))
one-of
type(numeric.abserror(0.01))


ID is: 3560 Seed is: 5743

What is friction?

Joanna pushes a crate across a rough floor. She observes the crate slow down as it slides across the rough floor.

Joanna's friend, Jacques, makes four statements about the nature of the frictional force that acts on the crate.

  1. The kinetic frictional force always opposes the relative motion between two surfaces sliding past each other.
  2. The frictional force depends on the speed of the crate.
  3. The frictional force arises from tiny bumps in both surfaces which opposes relative motion.
  4. The frictional force comes from the electrostatic force.

Help Joanna classify each of these statements as true or false.

Answer:

ID is: 3560 Seed is: 9507

What is friction?

Mpho shoves a crate across a rough floor. He observes the crate slow down as it slides across the rough floor.

Mpho's friend, Nicole, makes four statements about the nature of the frictional force that acts on the crate.

  1. The frictional force comes from the gravitational force.
  2. The kinetic frictional force always opposes the relative motion between two surfaces sliding past each other.
  3. The frictional force arises from tiny bumps in both surfaces which opposes relative motion.
  4. The frictional force comes from the electrostatic force.

Help Mpho classify each of these statements as true or false.

Answer:


ID is: 1429 Seed is: 3405

Working with the coefficient of kinetic friction

A box is sliding across a rough surface. It experiences a normal force of magnitude 952 N. The coefficient of kinetic friction between the surface and the box (μk) is 0,26.

What is the magnitude of the kinetic frictional force (fk)?

INSTRUCTION: Round your answer to two decimal places.
Answer:

fk= N

one-of
type(numeric.abserror(0.01))

ID is: 1429 Seed is: 7283

Working with the coefficient of kinetic friction

A box is sliding across a rough surface. It experiences a normal force of magnitude 450 N. The magnitude of the kinetic frictional force (fk) is 159,8 N.

What is the coefficient of kinetic friction (μk)?

INSTRUCTION: Round your answer to two decimal places.
Answer:

μk=

one-of
type(numeric.abserror(0.01))


ID is: 3660 Seed is: 3795

Proportional reasoning with fsmax, μs, and FN

The relationship fsmax=μsFN is a useful equation in mechanics.

fsmax is the maximum static frictional force, μs is the coefficient of static friction, and FN is the normal force.

  1. For a fixed coefficient of static friction, what can we say about the relationship between the maximum static frictional force and the normal force?

    Answer:

    The maximum static frictional force is the normal force.

  2. Consider the options below and choose the one that represents the relationship between the maximum static frictional force and the normal force symbolically:

    A fsmax=FN
    B fsmax>FN
    C fsmax1FN
    D fsmax<FN
    E fsmaxFN
    Answer:

    The correct option is .

  3. Consider two scenarios in which the same object is pushed into the same surface by different amounts. The normal force of the object in the second scenario is 4 times bigger than the normal force of the object in the first scenario.

    How does the maximum static frictional force in the second scenario compare to the maximum static frictional force in the first scenario?

    Answer:

    The maximum static frictional force in the second scenario is the maximum static frictional force in the first scenario.


ID is: 3660 Seed is: 7909

Proportional reasoning with fsmax, μs, and FN

The relationship fsmax=μsFN is an important equation in mechanics.

fsmax is the maximum static frictional force, μs is the coefficient of static friction, and FN is the normal force.

  1. For a constant coefficient of static friction, what can we say about the relationship between the maximum static frictional force and the normal force?

    Answer:

    The maximum static frictional force is the normal force.

  2. Consider the options below and choose the one that represents the relationship between the maximum static frictional force and the normal force symbolically:

    A fsmax=FN
    B fsmax>FN
    C fsmaxFN
    D fsmax<FN
    E fsmax1FN
    Answer:

    The correct option is .

  3. Consider two scenarios in which the same object is pushed into the same surface by different amounts. The normal force of the object in the second scenario is 9 times bigger than the normal force of the object in the first scenario.

    How does the maximum static frictional force in the second scenario compare to the maximum static frictional force in the first scenario?

    Answer:

    The maximum static frictional force in the second scenario is the maximum static frictional force in the first scenario.



ID is: 3744 Seed is: 7167

Experiment: Friction and the normal force

Abiodun and Lefu perform an experiment to determine the relationship between the normal force and the kinetic frictional force.

They use the following method in their experiment:

  1. Connect a spring balance to a block of known mass using a string.
  2. Place this block on a wooden surface.
  3. Pull on the spring balance so that the block moves with a constant velocity.
  4. Record the reading on the spring balance. This is the magnitude of the applied pulling force (Fpull).
  5. Add a known mass piece on top of the block. This will change the normal force.
  6. Repeat Steps 3 - 5 until you have five pairs of data.
  1. Which one of the following is the dependent variable in their experiment?

    A the kinetic frictional force
    B the material of the block
    C the mass of the system
    D the table surface used
    Answer:

    The dependent variable is:

  2. Abiodun pulls on the spring balance and Lefu records the force. They produce the following table of results of the magnitude of the applied pulling force (Fpull) for a given system mass (M).

    M(kg) Fpull(N)
    0,42 1,4
    0,52 1,8
    0,62 2,1
    0,72 2,6
    0,82 2,9

    Determine the following when the mass of the system is 0,52 kg:

    1. The magnitude of the normal force experienced by the system.
    2. The magnitude of the kinetic frictional force experienced by the system.
    INSTRUCTION:
    • Round both of your final answers to one decimal place.
    • Use the values given here for any physical constants that you may need.
    Answer:

    When the mass of the system is 0,52 kg:

    1. FN=
    2. fk=
    numeric
    numeric
  3. In a scientific experiment we need to work with the data before we draw a conclusion.

    Abiodun and Lefu decide that they need to use their data to determine a best estimate for the coefficient of kinetic friction.

    1. Because they expect μk to be constant, one way to get this estimate is to determine the arithmetic mean (average). Use all the data points to calculate the average value of the coefficient of kinetic friction.

      INSTRUCTION: Round your answer to two decimal places.
    2. Which other method could be used to determine a best estimate for μk?

      A Calculate the gradient of a graph of the normal force plotted against the kinetic frictional force
      B Calculate the gradient of a graph of the kinetic frictional force plotted against the normal force.
      C Calculate the y-intercept of a graph of the kinetic frictional force plotted against the normal force.
      D Calculate the y-intercept of a graph of the normal force plotted against the kinetic frictional force.
    3. Help Abiodun and Lefu draw a suitable conclusion for their experiment.

      W The tension in the string is inversely proportional to the coefficient of kinetic friction.
      X The kinetic frictional force is directly proportional to the normal force.
      Y The material of the block is directly proportional to the normal force.
      Z The mass of the system is inversely proportional to the tension in the string.
    Answer:
    1. μk,avg=
    2. Another method to get the best estimate of μk is to:
    3. Abiodun and Lefu can conclude that:
    numeric

ID is: 3744 Seed is: 9178

Experiment: Friction and the normal force

Aisha and Mustapha perform an experiment to determine the relationship between the normal force and the kinetic frictional force.

They use the following method in their experiment:

  1. Connect a spring balance to a block of known mass using a string.
  2. Place this block on a wooden surface.
  3. Pull on the spring balance so that the block moves with a constant velocity.
  4. Record the reading on the spring balance. This is the magnitude of the applied pulling force (Fpull).
  5. Add a known mass piece on top of the block. This will change the normal force.
  6. Repeat Steps 3 - 5 until you have five pairs of data.
  1. Which one of the following is the independent variable in their experiment?

    A the material of the block
    B the tension in the string
    C the normal force
    D the table surface used
    Answer:

    The independent variable is:

  2. Aisha pulls on the spring balance and Mustapha records the force. They produce the following table of results of the magnitude of the applied pulling force (Fpull) for a given system mass (M).

    M(kg) Fpull(N)
    0,60 2,4
    0,70 2,8
    0,80 3,4
    0,90 3,7
    1,00 3,8

    Determine the following when the mass of the system is 0,90 kg:

    1. The magnitude of the normal force experienced by the system.
    2. The magnitude of the kinetic frictional force experienced by the system.
    INSTRUCTION:
    • Round both of your final answers to one decimal place.
    • Use the values given here for any physical constants that you may need.
    Answer:

    When the mass of the system is 0,90 kg:

    1. FN=
    2. fk=
    numeric
    numeric
  3. In a scientific experiment we need to work with the data before we draw a conclusion.

    Aisha and Mustapha decide that they need to use their data to determine a best estimate for the coefficient of kinetic friction.

    1. Because they expect μk to be constant, one way to get this estimate is to determine the arithmetic mean (average). Use all the data points to calculate the average value of the coefficient of kinetic friction.

      INSTRUCTION: Round your answer to two decimal places.
    2. Which other method could be used to determine a best estimate for μk?

      A Calculate the gradient of a graph of the normal force plotted against the kinetic frictional force
      B Calculate the x-intercept of a graph of the kinetic frictional force plotted against the normal force.
      C Calculate the gradient of a graph of the kinetic frictional force plotted against the normal force.
      D Calculate the x-intercept of a graph of the normal force plotted against the kinetic frictional force.
    3. Help Aisha and Mustapha draw a suitable conclusion for their experiment.

      W The normal force is inversely proportional to the kinetic frictional force.
      X The applied pulling force is inversely proportional to the coefficient of kinetic friction.
      Y The applied pulling force is directly proportional to the table surface used.
      Z The kinetic frictional force is directly proportional to the normal force.
    Answer:
    1. μk,avg=
    2. Another method to get the best estimate of μk is to:
    3. Aisha and Mustapha can conclude that:
    numeric


ID is: 3765 Seed is: 2212

Experiment: Determining the coefficient of static friction

Eric performs an investigation to find out the coefficient of static friction for various materials when in contact with wood.

He makes use of a block sliding down an inclined plane. The block is covered in various materials: cellophane, paper, cardboard, tinfoil, and waxpaper.

This is the method he follows from his textbook:

  1. Measure the length of the plank of wood.
  2. Cover the bottom of the block with one of the materials.
  3. Place the block near one edge of the plank.
  4. Slowly increase the angle of the plank until the block just begins to move. Measure the critical height (hc) of the block when it just starts to move using a metre-rule.
  5. Use trigonometry to determine the critical angle (αc). This is the angle at which the block will just begin to move.
  6. Hence determine the coefficient of static friction using μs=tan(αc).
  7. Complete Steps 2 - 6 for all the different block coverings you will be investigating.

The following diagram shows the experimental setup:

  1. Eric measured the length of the plank to be 1,420 m. He obtains the following heights for each block covering:

    Covering Height (m)
    cellophane 0,35
    paper 0,61
    cardboard 0,71
    tinfoil 0,53
    waxpaper 0,59

    Determine the critical angle (αc) when the block was covered with cardboard.

    Hence determine the coefficient of static friction for cardboard on wood.

    INSTRUCTION: Round both of your final answers to two decimal places.
    Answer:

    When the block is covered with cardboard:

    • αc= °
    • μs=
    numeric
    numeric
  2. Which covering has the lowest coefficient of static friction?

    Answer:

    The covering with the lowest μs is .

  3. The following table contains various statements relating to the experiment.

    A Several different height readings for the same block covering should be taken.
    B The critical height of the block might be longer than the metre-rule.
    C Smoother surfaces have fewer irregularities in their surface that can interlock with each other. This reduces the electrostatic force of attraction between surface atoms which makes it is easier for surfaces to start sliding past each other.
    D The height at which the block starts to slide is higher for block coverings with higher coefficients of static friction.

    Match an appropriate statement from the above table (A - D) to each of the following:

    1. Something that will improve the results of the experiment.
    2. A factor that may add to the uncertainty in the results of the experiment.
    3. An explanation of an observed trend, using theory.
    Answer:
    1. : something that will improve the results of the experiment.
    2. : a factor that may add to the uncertainty in the results of the experiment.
    3. : an explanation of an observed trend, using theory.

ID is: 3765 Seed is: 3759

Experiment: Determining the coefficient of static friction

Abayomi performs an investigation to find out the coefficient of static friction for various materials when in contact with wood.

He makes use of a block sliding down an inclined plane. The block is covered in various materials: waxpaper, cellophane, sandpaper, cardboard, and tinfoil.

This is the method he follows from his textbook:

  1. Measure the length of the plank of wood.
  2. Cover the bottom of the block with one of the materials.
  3. Place the block near one edge of the plank.
  4. Slowly increase the angle of the plank until the block just begins to move. Measure the critical height (hc) of the block when it just starts to move using a metre-rule.
  5. Use trigonometry to determine the critical angle (αc). This is the angle at which the block will just begin to move.
  6. Hence determine the coefficient of static friction using μs=tan(αc).
  7. Complete Steps 2 - 6 for all the different block coverings you will be investigating.

The following diagram shows the experimental setup:

  1. Abayomi measured the length of the plank to be 1,120 m. He obtains the following heights for each block covering:

    Covering Height (m)
    waxpaper 0,45
    cellophane 0,26
    sandpaper 0,70
    cardboard 0,56
    tinfoil 0,43

    Determine the critical angle (αc) when the block was covered with tinfoil.

    Hence determine the coefficient of static friction for tinfoil on wood.

    INSTRUCTION: Round both of your final answers to two decimal places.
    Answer:

    When the block is covered with tinfoil:

    • αc= °
    • μs=
    numeric
    numeric
  2. Which covering has the second lowest coefficient of static friction?

    Answer:

    The covering with the second lowest μs is .

  3. The following table contains various statements relating to the experiment.

    A Several different height readings for the same block covering should be taken.
    B Different surface combinations have different coefficients of static friction.
    C It might be difficult to judge the angle at which the block just starts to slide down the slope.
    D Smoother surfaces have fewer irregularities in their surface that can interlock with each other. This reduces the electrostatic force of attraction between surface atoms which makes it is easier for surfaces to start sliding past each other.

    Match an appropriate statement from the above table (A - D) to each of the following:

    1. Something that will improve the results of the experiment.
    2. An explanation of an observed trend, using theory.
    3. A factor that may add to the uncertainty in the results of the experiment.
    Answer:
    1. : something that will improve the results of the experiment.
    2. : an explanation of an observed trend, using theory.
    3. : a factor that may add to the uncertainty in the results of the experiment.

5. Force and free-body diagrams



ID is: 3327 Seed is: 2323

Definitions: Force and free-body diagrams

Define a free-body diagram using the dropdown menus below.

Answer:

A free-body diagram shows the of all forces exerted on an object using to represent the force vectors. The object is represented by and all force vectors have their tails at the and point .


ID is: 3327 Seed is: 116

Definitions: Force and free-body diagrams

Define a free-body diagram using the dropdown menus below.

Answer:

A free-body diagram shows the of all forces exerted on an object using to represent the force vectors. The object is represented by and all force vectors have their tails at the and point .



ID is: 3518 Seed is: 6636

Free-body and force diagrams

A number of different forces are acting on a crate. Gabisile draws the following diagram to show all these forces.

Did Gabisile draw a free-body diagram or a force diagram?

Give a reason for your answer from the table below.

A the object is represented by a dot with each force acting on the object drawn as an arrow pointing away from the dot
B the object is represented by an outline of the actual shape of the object with each force acting on the object drawn as an arrow pointing away from the point on the object at which the force acts
Answer:

Gabisile drew a diagram.

We know this because .


ID is: 3518 Seed is: 4295

Free-body and force diagrams

A number of different forces are acting on a crate. Gabisile draws the following diagram to show all these forces.

Did Gabisile draw a free-body diagram or a force diagram?

Give a reason for your answer from the table below.

A the object is represented by an outline of the actual shape of the object with each force acting on the object drawn as an arrow pointing away from the point on the object at which the force acts
B the object is represented by a dot with each force acting on the object drawn as an arrow pointing away from the dot
Answer:

Gabisile drew a diagram.

We know this because .



ID is: 3800 Seed is: 7806

Getting force and free-body diagrams right!

A system of two blocks is pulled to the left across a rough surface.

Angelique tries to draw a force diagram to show all the forces acting on the block on the left.

This is the diagram that she draws:

The diagram has the correct number of forces, but there is a problem with the diagram! What mistake did Angelique make?

A The forces have incorrect labels.
B The tail of at least one force vector is in the wrong place.
C A free-body diagram was drawn instead of a force diagram.
D The forces have incorrect arrowheads.
Answer:

The mistake made was:


ID is: 3800 Seed is: 3978

Getting force and free-body diagrams right!

A box is in a lift which is accelerating up.

Adebiyi tries to draw a free-body diagram to show all the forces acting on the box.

This is the diagram that he draws:

The diagram has the correct number of forces, but there is a problem with the diagram! What mistake did Adebiyi make?

A A force diagram was drawn instead of a free-body diagram.
B The forces have not been labelled.
C The forces have incorrect arrowheads.
D One of the forces is pointing in the wrong direction.
Answer:

The mistake made was:



ID is: 3895 Seed is: 2316

Force and free-body diagrams: systems

A system of two blocks is pulled up a smooth inclined plane.

The string joining the two blocks is inextensible (it can't be stretched) and it is pulled tight.

Jezile draws a diagram to show all the forces acting on one of the blocks.

This is the diagram that she draws:

Which one of the options below best describes the diagram that Jezile drew?

A A free-body diagram for the higher block.
B A force diagram for the higher block.
C A force diagram for the lower block.
D A free-body diagram for the lower block.
Answer:

The correct choice is:


ID is: 3895 Seed is: 2651

Force and free-body diagrams: systems

A system of two blocks is pulled down a smooth ramp.

The string joining the two blocks is inextensible (it can't be stretched) and it is pulled tight.

Chukwuma draws a diagram to show all the forces acting on one of the blocks.

This is the diagram that he draws:

Which one of the options below best describes the diagram that Chukwuma drew?

A A force diagram for the higher block.
B A free-body diagram for the lower block.
C A free-body diagram for the higher block.
D A force diagram for the lower block.
Answer:

The correct choice is:



ID is: 3615 Seed is: 8312

Multiple choice: Matching free-body diagrams to objects

A block of mass m1 is connected to another block of mass m2 by a light inextensible cable. This system of blocks is then suspended from the ceiling by the top block, using the same type of cable.

  1. Draw labelled free-body diagrams indicating all the forces acting on each block.

    Now compare your diagrams to the two diagrams given below and answer the questions that follow.

    Diagram A

    Diagram B

    1. Which diagram is the free-body diagram for the bottom block?
    2. Which force does Force Y represent?
    Answer:
    1. Diagram is the free-body diagram for the bottom block.
    2. Force Y represents the force acting on the block.

ID is: 3615 Seed is: 7775

Multiple choice: Matching free-body diagrams to objects

A block of mass m1 is connected to another block of mass m2 by a light inextensible rope. This system of blocks is then suspended from the ceiling by the top block, using the same type of rope.

  1. Draw labelled free-body diagrams indicating all the forces acting on each block.

    Now compare your diagrams to the two diagrams given below and answer the questions that follow.

    Diagram A

    Diagram B

    1. Which diagram is the free-body diagram for the top block?
    2. Which force does Force X represent?
    Answer:
    1. Diagram is the free-body diagram for the top block.
    2. Force X represents the force acting on the block.


ID is: 3671 Seed is: 899

Identifying number of forces acting on systems on inclined ramps

Box 1 is connected to Box 2 by a light inextensible string. The same type of string is attached to Box 2, run over a light frictionless pulley, and connected to a motor.

The motor pulls the system up a smooth ramp inclined at an angle α to the horizontal. The motor applies a constant force which causes the system to accelerate. The force applied by the motor is parallel to the ramp as shown in the diagram below. Ignore all forms of friction.

Draw labelled free-body diagrams indicating all the forces acting on the both boxes.

How many forces should there be in these diagrams?Remember that a free-body diagram should contain actual forces, not components of forces.

Answer:
  1. There is/are force(s) in the free-body diagram for the bottom box.
  2. There is/are force(s) in the free-body diagram for the top box.
one-of
type(string)
one-of
type(string)

ID is: 3671 Seed is: 3109

Identifying number of forces acting on systems on inclined planes

Box 1 is connected to Box 2 by a light inextensible rope. The same type of rope is attached to Box 2, run over a light frictionless pulley, and connected to a motor.

The motor pulls the system up a smooth plane inclined at an angle α to the horizontal. The motor applies a constant force which causes the system to accelerate. The force applied by the motor is parallel to the plane as shown in the diagram below. Ignore all forms of friction.

Draw labelled free-body diagrams showing all the forces acting on the both boxes.

How many forces should there be in these diagrams?Remember that a free-body diagram should contain actual forces, not components of forces.

Answer:
  1. There is/are force(s) in the free-body diagram for the bottom box.
  2. There is/are force(s) in the free-body diagram for the top box.
one-of
type(string)
one-of
type(string)


ID is: 3667 Seed is: 9495

Mistakes in free-body diagrams!

Block 1 is connected to Block 2 by a light inextensible string. The system is pulled up a rough ramp inclined at α to the vertical, by means of a constant force parallel to the ramp as shown in the diagram below. The magnitude of the kinetic frictional force between the surface and Block 1 is fk,1.

Draw a labelled free-body diagram indicating all the forces acting on Block 1 as it moves up the ramp.

The free-body diagram given below contains a mistake. There is a problem with one of the forces.

Compare your free-body diagram to the given diagram to work out which force is the problem and what the mistake is.

Possible mistakes
1 The force is missing.
2 The force has the wrong direction.
3 The force should not be there.
Answer:

The force with the problem is the force.

The problem is .


ID is: 3667 Seed is: 8113

Mistakes in free-body diagrams!

Crate 1 is connected to Crate 2 by a light inextensible rope. The system is pulled up a smooth plane inclined at α to the horizontal, by means of a constant force parallel to the plane as shown in the diagram below. All forms of friction can be ignored.

Draw a labelled free-body diagram indicating all the forces acting on Crate 1 as it moves up the plane.

The free-body diagram given below contains a mistake. There is a problem with one of the forces.

Compare your free-body diagram to the given diagram to work out which force is the problem and what the mistake is.

Possible mistakes
1 The force is missing.
2 The force has the wrong direction.
3 The force should not be there.
Answer:

The force with the problem is the force.

The problem is .



ID is: 3894 Seed is: 3907

Getting force and free-body diagrams right!

A system of two blocks is pulled to the left across a rough surface.

Limpho draws the following force diagram to show all the forces acting on the block on the left.

The diagram has the correct number of forces, but one of the forces is pointing in the wrong direction. Which force is incorrect?

A Fg
B f
C FN
D T
E Fpull
Answer:

The force pointing in the wrong direction is:


ID is: 3894 Seed is: 64

Getting force and free-body diagrams right!

A system of two packages is pulled down a smooth slope.

Faruq draws the following force diagram to show all the forces acting on the higher package.

The diagram has the correct number of forces, but one of the forces is pointing in the wrong direction. Which force is incorrect?

A T
B Fg
C FN
Answer:

The force pointing in the wrong direction is:



ID is: 4566 Seed is: 9113

Free-body diagrams on a rough horizontal surface

Adapted from DBE Nov 2015 Grade 11, P1, Q3
Physical constants · Physics formulas

A 70 kg block is placed on a rough horizontal surface. A constant force (F) pushes the block and the block moves across the surface at a constant speed as shown in the diagram below. The coefficient of kinetic friction (μk) between the block and the surface is 0,42.

Draw a labelled free-body diagram showing all the forces acting on the block.

For each of the free-body diagrams below use the table of options (W to Z) to say if the diagram is correct or to explain why it is incorrect.

Answer:
Options
W The diagram is correct!
X The normal force has the wrong length.
Y The frictional force is missing.
Z The frictional force has the wrong direction.

Diagram I

Diagram II

Diagram III

Diagram IV


ID is: 4566 Seed is: 1631

Free-body diagrams on a rough horizontal surface

Adapted from DBE Nov 2015 Grade 11, P1, Q3
Physical constants · Physics formulas

A 60 kg block is placed on a rough horizontal surface. A constant force (F) pulls the block, but the block remains at rest as shown in the diagram below. The coefficient of static friction (μs) between the block and the surface is 0,58. If the magnitude of the applied force were any larger, the block would begin to move.

Draw a labelled free-body diagram showing all the forces acting on the block.

For each of the free-body diagrams below use the table of options (W to Z) to say if the diagram is correct or to explain why it is incorrect.

Answer:
Options
W The diagram is correct!
X The normal force has the wrong length.
Y The frictional force has the wrong direction.
Z The normal force has the wrong direction.

Diagram I

Diagram II

Diagram III

Diagram IV

6. Components and resultants of forces



ID is: 1427 Seed is: 9070

Resolving the gravitational force into components

A gravitational force of Fg=128 N is acting straight down on a block. The block is on an inclined plane with a slope inclined at an angle of 34° with the horizontal.

Calculate the components of the force due to gravity parallel and perpendicular to the slope.

INSTRUCTION: Round your answers to one decimal place.
Answer:

Fg,= N

Fg,= N

numeric
numeric

ID is: 1427 Seed is: 9668

Resolving the gravitational force into components

A gravitational force of Fg=176 N is acting straight down on a block. The block is on an inclined plane with a slope inclined at an angle of 25° with the horizontal.

Calculate the components of the force due to gravity parallel and perpendicular to the slope.

INSTRUCTION: Round your answers to one decimal place.
Answer:

Fg,= N

Fg,= N

numeric
numeric


ID is: 1493 Seed is: 9583

Resultant force

Adebankole is pushing a trolley with a constant force of 48,77 N. The trolley is experiencing a force due to gravity of 160 N. A constant frictional force of 30,69 N is present.

What is the resultant force on the trolley?

INSTRUCTION: Round your answer to two decimal places.
Answer:

Fnet= N

one-of
type(numeric.abserror(0.01))

ID is: 1493 Seed is: 5490

Resultant force

Eric is pushing a trolley with a constant force of 108,3 N. The trolley is experiencing a force due to gravity of 140 N. A constant frictional force of 79,54 N is present.

What is the resultant force on the trolley?

INSTRUCTION: Round your answer to two decimal places.
Answer:

Fnet= N

one-of
type(numeric.abserror(0.01))


ID is: 3773 Seed is: 599

Adding vector force components

Five forces are acting on a book. The following diagram shows the scenario as seen from above.

Three of the forces are aligned along the north-south axis. The other two forces are aligned along the east-west axis.

Calculate:

  1. The net force along the north-south axis.
  2. The net force along the east-west axis.
INSTRUCTIONS:
  • Give the magnitudes of both components to the nearest newton.
  • Use the drop-down menus to show the directions or to indicate if there is no direction.
Answer:
  1. Fnet,north-south= N .
  2. Fnet,east-west= N .
numeric
numeric

ID is: 3773 Seed is: 7201

Adding vector force components

Five forces are acting on a cupboard. The following diagram shows the scenario as seen from above.

Three of the forces are aligned along the east-west axis. The other two forces are aligned along the north-south axis.

Calculate:

  1. The net force along the east-west axis.
  2. The net force along the north-south axis.
INSTRUCTIONS:
  • Give the magnitudes of both components to the nearest newton.
  • Use the drop-down menus to show the directions or to indicate if there is no direction.
Answer:
  1. Fnet,east-west= N .
  2. Fnet,north-south= N .
numeric
numeric


ID is: 1437 Seed is: 5930

Resolving the gravitational force into components

A gravitational force of Fg=174 N is acting straight down on a block on an inclined slope.

If the magnitude of the component of the gravitational force perpendicular to the slope is 164,4 N, what is the incline (angle) of the slope as measured from the horizontal?

INSTRUCTION: Round your answer to one decimal place.
Answer: θ= °
one-of
type(numeric.abserror(0.1))

ID is: 1437 Seed is: 475

Resolving the gravitational force into components

A gravitational force of Fg=164 N is acting straight down on a block on an inclined slope.

If the magnitude of the component of the gravitational force perpendicular to the slope is 143,3 N, what is the incline (angle) of the slope as measured from the horizontal?

INSTRUCTION: Round your answer to one decimal place.
Answer: θ= °
one-of
type(numeric.abserror(0.1))


ID is: 1501 Seed is: 2831

Resultants

Two forces, 8 N and 4 N, act at an angle at the same point.

Which one of the following can be the magnitude of the resultant of these two forces?

Answer:

ID is: 1501 Seed is: 6817

Resultants

Two forces, 9 N and 3 N, act at an angle at the same point.

Which one of the following cannot be the magnitude of the resultant of these two forces?

Answer:


ID is: 3770 Seed is: 2404

Adding vector force components

Five forces are acting on an object. The following diagram shows the scenario as seen from the side.

Three of the forces are aligned along the y-axis. The other two forces are aligned along the x-axis.

Calculate the magnitude and direction of the net force exerted on the object.

INSTRUCTIONS:
  • Round both the magnitude and direction to two decimal places.
  • Specify the direction as an angle anticlockwise from the negative y-axis.
Answer:

Fnet= N at ° anticlockwise from the negative y-axis.

one-of
type(numeric.abserror(0.01))
one-of
type(numeric.abserror(0.01))

ID is: 3770 Seed is: 705

Adding vector force components

Five forces are acting on a cupboard. The following diagram shows the scenario as seen from above.

Three of the forces are aligned along the east-west axis. The other two forces are aligned along the north-south axis.

Calculate the magnitude and direction of the net force exerted on the cupboard.

INSTRUCTIONS:
  • Round both the magnitude and direction to two decimal places.
  • Specify the direction as an angle south of west.
Answer:

Fnet= N at ° south of west.

one-of
type(numeric.abserror(0.01))
one-of
type(numeric.abserror(0.01))


ID is: 3670 Seed is: 5201

Identifying the correct expression

Crate 1 is connected to Crate 2 by a light inextensible rope. The same type of rope is attached to Crate 2, run over a light frictionless pulley, and connected to a motor.

The motor pulls the system up a rough ramp inclined at an angle α to the horizontal. The motor applies a constant force which causes the system to accelerate. The force applied by the motor is parallel to the ramp as shown in the diagram below. Do not ignore friction.

The following table contains possible expressions for the magnitude of the net force experienced by the two crates. Identify which expression belongs with each crate.

W Tm1gcosαfk,1
X FmotorTm2gcosαfk,2
Y FmotorTm2gsinαfk,2
Z Tm1gsinαfk,1
Answer:
  1. The magnitude of the net force on the bottom crate is given by .
  2. The magnitude of the net force on the top crate is given by .

ID is: 3670 Seed is: 1912

Identifying the correct expression

Box 1 is connected to Box 2 by a light inextensible rope. The same type of rope is attached to Box 2, run over a light frictionless pulley, and connected to a motor.

The motor pulls the system up a smooth ramp inclined at an angle α to the vertical. The motor applies a constant force which causes the system to accelerate. The force applied by the motor is parallel to the ramp as shown in the diagram below. Ignore all forms of friction.

The following table contains possible expressions for the magnitude of the net force experienced by the two crates. Identify which expression belongs with each crate.

W Tm1gcosα
X Tm1gsinα
Y FmotorTm2gsinα
Z FmotorTm2gcosα
Answer:
  1. The magnitude of the net force on the bottom box is given by .
  2. The magnitude of the net force on the top box is given by .


ID is: 3746 Seed is: 4451

Vector components

Danjuma is pulling an object across the floor with a force F at an angle of 18° east of north. The following diagram (which is not to scale) shows the scenario as seen from above.

The component of the pulling force to the east is 53 N.

Calculate:

  1. the magnitude of the applied pulling force.
  2. the magnitude of the component of the pulling force to the north.
INSTRUCTION: Round both of your answers to two decimal places.
Answer:

F= N

Fnorth= N

one-of
type(numeric.abserror(0.01))
one-of
type(numeric.abserror(0.01))

ID is: 3746 Seed is: 3363

Vector components

Peter is pulling a box across the floor with a force F at an angle of 34° east of north. The following diagram (which is not to scale) shows the scenario as seen from above.

The component of the pulling force to the north is 225 N.

Calculate:

  1. the magnitude of the applied pulling force.
  2. the magnitude of the component of the pulling force to the east.
INSTRUCTION: Round both of your answers to two decimal places.
Answer:

F= N

Feast= N

one-of
type(numeric.abserror(0.01))
one-of
type(numeric.abserror(0.01))


ID is: 3747 Seed is: 1591

Vector components

Chibuike is pulling a crate across the floor with a force F at an angle of α to the vertical. The following diagram (which is not to scale) shows the scenario as seen from the side.

The vertical component of the pulling force is 57 N and the horizontal component of the pulling force is 37 N.

Calculate:

  1. the magnitude of the applied pulling force.
  2. the angle that describes the direction of the applied pushing force.
INSTRUCTION: Round both of your answers to two decimal places.
Answer:

F= N

α= °

one-of
type(numeric.abserror(0.01))
one-of
type(numeric.abserror(0.01))

ID is: 3747 Seed is: 584

Vector components

Chukwuma is pulling a box across the floor with a force F at an angle of α to the vertical. The following diagram (which is not to scale) shows the scenario as seen from the side.

The vertical component of the pulling force is 88 N and the horizontal component of the pulling force is 53 N.

Calculate:

  1. the magnitude of the applied pulling force.
  2. the angle that describes the direction of the applied pushing force.
INSTRUCTION: Round both of your answers to two decimal places.
Answer:

F= N

α= °

one-of
type(numeric.abserror(0.01))
one-of
type(numeric.abserror(0.01))


ID is: 3748 Seed is: 9455

Vector components

Yengwayo is pulling a cupboard across the floor with a force of 300 N at an angle of 25° to the horizontal. The following diagram (which is not to scale) shows the scenario as seen from the side.

Resolve the pulling force into horizontal (x) and vertical (y) components.

INSTRUCTIONS:
  • Give magnitudes of the components.
  • Round both of your answers to two decimal places.
Answer:

The magnitudes of the components of the pulling force are:

Fx= N

Fy= N

one-of
type(numeric.abserror(0.01))
one-of
type(numeric.abserror(0.01))

ID is: 3748 Seed is: 7504

Vector components

Kayla is pulling an object across the floor with a force of 250 N at an angle of 34° west of north. The following diagram (which is not to scale) shows the scenario as seen from above.

Resolve the pulling force into components to the north and west.

INSTRUCTIONS:
  • Give magnitudes of the components.
  • Round both of your answers to two decimal places.
Answer:

The magnitudes of the components of the pulling force are:

Fnorth= N

Fwest= N

one-of
type(numeric.abserror(0.01))
one-of
type(numeric.abserror(0.01))


ID is: 1428 Seed is: 1168

Identifying vector components

Consider the following diagram of a bus parked on a hill:

Choose the vector which best describes the normal force acting on the bus.

A Fup D Fdown
B F,up E F,down
C F,left F F,right
Answer:

ID is: 1428 Seed is: 529

Identifying vector components

Consider the following diagram of a bus parked on a hill:

Choose the vector which best describes the gravitational force acting on the bus.

A Fup D Fdown
B F,up E F,down
C F,left F F,right
Answer:


ID is: 3524 Seed is: 2647

Components and inclined planes

Nneka is moving house. She is pulling a heavy box with mass m up a ramp onto the moving van. The ramp is inclined at an angle α to the vertical. The force has a magnitude F and acts at an angle β to the ramp as shown in the diagram below.

  1. Write down expressions for the magnitude of the parallel component of the pulling force (F) as well as the magnitude of the parallel component of the gravitational force (Fg,).

    TIP: Which components are calculated using cos and which are calculated using sin depends on the line from which the angle is measured (the horizontal, the vertical, from the normal of the ramp, from the ramp). Always go back to the definitions of the trig functions rather than trying to remember results like these.

    You can use any of the following variables and trigonometric functions in your answers:

    m;β;F;α;gsin;cos;tan
    INSTRUCTIONS:
    • you can type a for the symbol α
    • you can type B for the symbol β
    • put brackets around the angle of the trigonometric function e.g. type tan(a) for tanα
    Answer:

    The parallel component of the pulling force:
    F=

    The parallel component of the gravitational force:
    Fg,=

    one-of
    type(expression)
    one-of
    type(expression)
  2. Nneka is pulling the heavy box with a force of magnitude 380 N at an angle 21° to the ramp. The heavy box has a mass 49 kg and the ramp is inclined at an angle 46° to the vertical.

    Calculate the components of the pulling force and the gravitational force that are parallel to the ramp.

    INSTRUCTION: Round your answers to two decimal places.
    Answer:

    F=
    Fg,=

    one-of
    type(numeric.abserror(0.01))
    numeric

ID is: 3524 Seed is: 5849

Components and inclined planes

Lefu is moving house. He is pulling a desk with mass m up a ramp onto the moving truck. The ramp is inclined at an angle α to the vertical. The force has a magnitude F and acts at an angle β to the ramp as shown in the diagram below.

  1. Write down expressions for the magnitude of the parallel component of the pulling force (F) as well as the magnitude of the parallel component of the gravitational force (Fg,).

    TIP: Which components are calculated using cos and which are calculated using sin depends on the line from which the angle is measured (the horizontal, the vertical, from the normal of the ramp, from the ramp). Always go back to the definitions of the trig functions rather than trying to remember results like these.

    You can use any of the following variables and trigonometric functions in your answers:

    m;α;g;F;βtan;cos;sin
    INSTRUCTIONS:
    • you can type a for the symbol α
    • you can type B for the symbol β
    • put brackets around the angle of the trigonometric function e.g. type tan(a) for tanα
    Answer:

    The parallel component of the pulling force:
    F=

    The parallel component of the gravitational force:
    Fg,=

    one-of
    type(expression)
    one-of
    type(expression)
  2. Lefu is pulling the desk with a force of magnitude 460 N at an angle 20° to the ramp. The desk has a mass 89 kg and the ramp is inclined at an angle 54° to the vertical.

    Calculate the components of the pulling force and the gravitational force that are parallel to the ramp.

    INSTRUCTION: Round your answers to two decimal places.
    Answer:

    F=
    Fg,=

    one-of
    type(numeric.abserror(0.01))
    numeric

7. Newton's first law



ID is: 3768 Seed is: 2666

Falling for physics!

  1. Adebimpe is standing in a train which is moving along a straight track. The train suddenly changes speed. Adebimpe isn't holding onto anything and stumbles forward.

    Did the train speed up or slow down?

    Answer:

    The train must have .

  2. Which one of the following gives the best reason why Adebimpe stumbles forward?

    A The floor of the train exerts a net force on her.
    B Her inertia is conserved.
    C It follows from Newton's first law of motion.
    D Kinetic energy is always conserved.
    Answer:

    The correct option is:


ID is: 3768 Seed is: 1888

Falling for physics!

  1. Bonani is standing in a train which is moving along a straight track. The train suddenly speeds up. Bonani isn't holding onto anything and stumbles.

    In which direction will Bonani stumble?

    Answer:

    Bonani will stumble .

  2. Which one of the following gives the best reason why Bonani stumbles backward?

    A It follows from Newton's first law of motion.
    B The floor of the train exerts a net force on him.
    C Kinetic energy is always conserved.
    D His inertia is conserved.
    Answer:

    The correct option is:



ID is: 3769 Seed is: 1813

Reasoning with Newton's first law

A parcel is loose on the smooth back seat of a car. The driver of the car turns a corner sharply. The parcel is seen to move to one side of the car.

Classify each of the following four statements as correct reasons or incorrect reasons for why the parcel is seen to move to the side.

Answer:
  1. There is a reaction force that pushes the parcel to the side.
  2. The parcel keeps moving at a constant speed, but not direction.
  3. The parcel keeps moving at a constant velocity.
  4. The parcel keeps moving in the same direction, with the same speed.

ID is: 3769 Seed is: 8357

Reasoning with Newton's first law

A box is loose on the smooth back seat of a car. The driver of the car turns a corner sharply. The box is seen to move to one side of the car.

Classify each of the following four statements as correct reasons or incorrect reasons for why the box is seen to move to the side.

Answer:
  1. The influence of gravity on the box is reduced.
  2. The box has inertia and so resists a change in motion.
  3. The mass of the box is smaller than that of the car.
  4. The box experiences a zero net force.


ID is: 3766 Seed is: 3924

MCQ: Falling for physics!

Lindiwe is standing in a stationary train which suddenly starts to move. She isn't holding onto anything and falls backward!

Lindiwe falls backward because ...

A the floor of the train exerts a net force on her.
B of conservation of inertia.
C her mass opposes a change in motion.
D of Newton's third law of motion.
Answer: The correct option is:

ID is: 3766 Seed is: 1947

MCQ: Falling for physics!

Mphikeleli is standing in a stationary bus which suddenly starts to move. He isn't holding onto anything and falls backward!

Mphikeleli falls backward because ...

A of kinetic energy conservation.
B of conservation of inertia.
C he experiences a zero net force.
D of Newton's third law of motion.
Answer: The correct option is:


ID is: 3767 Seed is: 1066

MCQ: Newton's first law

A book is loose on the smooth back seat of a car. The driver of the car turns a corner sharply. The book is observed to slide to one side of the car.

Which one of the following statements could not be used as reason for why the book is observed to slide to the side?

A The book keeps moving at a constant velocity.
B The influence of gravity on the book is reduced.
C The book keeps moving in the same direction, with the same speed.
D The book experiences a zero net force.
Answer: The incorrect reason is:

ID is: 3767 Seed is: 6568

MCQ: Newton's first law

An object is loose on the smooth back seat of a car. The driver of the car turns a corner sharply. The object is seen to slide to one side of the car.

Which one of the following statements could be used as reason for why the object is seen to slide to the side?

A The car has changed direction, but the object keeps moving in a straight line.
B There is a resultant force on the object.
C There is a reaction force that pushes the object to the side.
D The mass of the object is smaller than that of the car.
Answer: The correct reason is:


ID is: 3290 Seed is: 6971

Multiple choice: Newton's first law

Four different learners were asked to state what they thought Newton’s first law of motion means. Three of the learners have incorrect interpretations and one has a correct interpretation.

Which one of the following statements is correct?

A Objects resist being in motion which is why they slow down.
B Objects move at a constant velocity only if they do not experience any forces.
C Objects tend to remain at rest or in uniform motion which results from inertia.
D Objects change how they move because of their inertia.
Answer:

The answer is: .


ID is: 3290 Seed is: 3698

Multiple choice: Newton's first law

Four different learners were asked to state what they thought Newton’s first law of motion means. Three of the learners have correct interpretations and one has an incorrect interpretation.

Which one of the following statements is incorrect?

A Objects move at a constant velocity only if they do not experience a net force.
B Objects tend to remain at rest or in uniform motion which results from inertia.
C Only if no forces act on an object will its motion remain constant.
D Objects resist changes to motion which is why they tend to remain in a uniform state of motion.
Answer:

The answer is: .



ID is: 3642 Seed is: 2755

Statement: Newton's first law

Adapted from DBE Nov 2015 & 2016 Grade 11, P1, Q3
Physical constants · Physics formulas

State Newton's first law of motion in words.

Answer:

A body will remain in a state of or moving with unless a is exerted on it.


ID is: 3642 Seed is: 9613

Statement: Newton's first law

Adapted from DBE Nov 2015 & 2016 Grade 11, P1, Q3
Physical constants · Physics formulas

State Newton's first law of motion in words.

Answer:

A body will remain in a state of or moving with unless a acts on it.



ID is: 3789 Seed is: 6808

Buckle up!

Sindisiwe is driving a car along a dirt road. A horse crosses the road and Sindisiwe immediately slams on the brakes and manages to stop in time. Fortunately, Sindisiwe was wearing a seatbelt and so was unharmed.

Use appropriate physics principles to complete the paragraph below which explains the importance of seatbelts.

Answer:

Initially, Sindisiwe and the car are travelling at the same velocity. When the driver slams on the brakes, a net force is exerted on the car which causes it to slow down.

If Sindisiwe were not strapped in with a seatbelt, she experience this net force. According to Newton's first law of motion, she would keep moving at the same velocity due to her inertia. She would be moving than the car. She would be flung relative to the car. She might go through the windscreen and get severe injuries.

But, because Sindisiwe is strapped in with a seatbelt, the seatbelt apply a net force on her. This will cause her to with the car.


ID is: 3789 Seed is: 4838

Buckle up!

Luyanda is driving a car along a dirt road. A monkey crosses the road and Luyanda immediately slams on the brakes and manages to stop in time. Fortunately, Luyanda was wearing a seatbelt and so was unharmed.

Use appropriate physics principles to complete the paragraph below which explains the importance of seatbelts.

Answer:

Initially, Luyanda and the car are travelling at the same velocity. When the driver slams on the brakes, a net force is exerted on the car which causes it to slow down.

If Luyanda were not strapped in with a seatbelt, she experience this net force. According to Newton's first law of motion, she would keep moving at the same velocity due to her inertia. She would be moving than the car. She would be flung relative to the car. She might go through the windscreen and get severe injuries.

But, because Luyanda is strapped in with a seatbelt, the seatbelt apply a net force on her. This will cause her to with the car.



ID is: 4014 Seed is: 7419

Multiple choice: Newton's laws

Adapted from WCED Metro Central Sep 2017 Grade 12, P1, Q1.1
Physical constants · Physics formulas

If you don't walk carefully while holding a full bowl of soup, the soup will easily spill over the edge of the bowl because of ...

A equal, but opposite forces and Newton's third law.
B acceleration and Newton's second law.
C resistance to change in motion and Newton's first law.
D gravity and Newton's universal law of gravitation.
Answer:

ID is: 4014 Seed is: 2339

Multiple choice: Newton's laws

Adapted from WCED Metro Central Sep 2017 Grade 12, P1, Q1.1
Physical constants · Physics formulas

If you don't walk carefully while holding a full bowl of soup, the soup will easily spill over the edge of the bowl because of ...

A momentum and Newton's second law in terms of momentum.
B gravity and Newton's universal law of gravitation.
C action-reaction pairs and Newton's third law.
D resistance to change in motion and Newton's law of inertia.
Answer:


ID is: 3641 Seed is: 4737

Definition: inertia

Use the drop-down menus below to define inertia.

Answer:

Inertia is the an object that causes it to its or .


ID is: 3641 Seed is: 9284

Definition: inertia

Use the drop-down menus below to define inertia.

Answer:

Inertia is the an object that causes it to its or .

8. Newton's second law



ID is: 1562 Seed is: 3715

Newton's second law

A person with a mass of 110 kg and a weight of 1 078 N stands on a scale (which gives a reading in newtons) inside a rocket that is accelerating downwards at 1,4 m·s2. What is the reading on the scale?

INSTRUCTION: Round your answer to the nearest newton.
Answer:

The reading on the scale is N.

numeric

ID is: 1562 Seed is: 8125

Newton's second law

A person with a mass of 100 kg and a weight of 980 N stands on a scale (which gives a reading in newtons) inside a rocket that is accelerating upwards at 3,4 m·s2. What is the reading on the scale?

INSTRUCTION: Round your answer to the nearest newton.
Answer:

The reading on the scale is N.

numeric


ID is: 3825 Seed is: 1028

Forces with an object on a slope

Adapted from DBE Feb-Mar 2017 Grade 12, P1, Q2
Physical constants · Physics formulas

In the diagram below (not to scale), a small object of mass 5 kg is sliding at a constant velocity of 1,9 m·s1 down a rough plane inclined at 18° to the horizontal surface.

At the bottom of the plane, the object continues sliding onto the rough horizontal surface and eventually comes to a stop.

The coefficient of kinetic friction between the object and the surface is the same for both inclined surface and the horizontal surface.

INSTRUCTIONS:
  • Round all final numerical answers to two decimal places.
  • You must use these values for any physical constants required in your calculations.
  1. What is the magnitude of the net force acting on the object while it is on the slope?

    Answer: The magnitude of the net force is N.
    numeric
  2. Draw a labelled free-body diagram for the object while it is on the inclined plane. Then answer the questions that follow.

    Answer:
    1. How many forces are there in the free-body diagram?
    2. Friction is .
    3. There an applied force.
    numeric
  3. Calculate the:

    1. Magnitude of the frictional force acting on the object while it is sliding down the inclined plane.
    2. Coefficient of kinetic friction between the object and the surface.
    3. Distance the object travels on the horizontal surface before it comes to a stop.
    Answer:
    1. fk=
    2. μk=
    3. Δx=
    one-of
    type(numeric.abserror(0.1))
    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))

ID is: 3825 Seed is: 5728

Forces with an object on a slope

Adapted from DBE Feb-Mar 2017 Grade 12, P1, Q2
Physical constants · Physics formulas

In the diagram below (not to scale), a small object of mass 2 kg is sliding at a constant velocity of 0,6 m·s1 down a rough plane inclined at 21° to the horizontal surface.

At the bottom of the plane, the object continues sliding onto the rough horizontal surface and eventually comes to a stop.

The coefficient of kinetic friction between the object and the surface is the same for both inclined surface and the horizontal surface.

INSTRUCTIONS:
  • Round all final numerical answers to two decimal places.
  • You must use these values for any physical constants required in your calculations.
  1. What is the magnitude of the net force acting on the object while it is on the slope?

    Answer: The magnitude of the net force is N.
    numeric
  2. Draw a labelled free-body diagram for the object while it is on the inclined plane. Then answer the questions that follow.

    Answer:
    1. How many forces are there in the free-body diagram?
    2. Friction is .
    3. There an applied force.
    numeric
  3. Calculate the:

    1. Magnitude of the frictional force acting on the object while it is sliding down the inclined plane.
    2. Coefficient of kinetic friction between the object and the surface.
    3. Distance the object travels on the horizontal surface before it comes to a stop.
    Answer:
    1. fk=
    2. μk=
    3. Δx=
    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))


ID is: 3639 Seed is: 9599

The relationship between m, Fnet, and a

Mass (m), net force (Fnet), and acceleration (a) are three important quantities in mechanics. They are related to each other through Newton's second law of motion.

Which one of the following equations correctly represents the relationship between these quantities?

A m=Fneta
B m=Fneta
C m=aFnet
Answer:

The correct equation is:


ID is: 3639 Seed is: 2079

The relationship between m, a, and Fnet

Mass (m), acceleration (a), and net force (Fnet) are three important quantities in mechanics. They are related to each other through Newton's second law of motion.

Which one of the following equations correctly represents the relationship between these quantities?

A a=Fnetm
B a=mFnet
C a=Fnetm
Answer:

The correct equation is:



ID is: 1465 Seed is: 6379

Newton's second law

A rocket has a mass of 1,21×106 kg and experiences a force of 1,1858×107 N due to gravity. The rocket is accelerating at 24,13 m·s2.

  1. What is the resultant force acting on the rocket?

    INSTRUCTION: Write your answer in scientific notation and then round it to three decimal places.
    Answer:

    Fnet= N

    numeric
  2. What driving force does the engine of the rocket need to exert on the rocket to maintain its acceleration?

    INSTRUCTION:
    • Use your unrounded answer from Question 1.
    • Write your answer in scientific notation and then round it to three decimal places.
    Answer:

    Fdrive= N

    numeric

ID is: 1465 Seed is: 2441

Newton's second law

A rocket has a mass of 1,10×106 kg and experiences a force of 1,0780×107 N due to gravity. The rocket is ignited and is launched with a driving force of 2,618×107 N upwards.

  1. What is the resultant force acting on the rocket?

    INSTRUCTION: Write your answer in scientific notation and then round it to three decimal places.
    Answer:

    Fnet= N

    numeric
  2. What is the acceleration of the rocket?

    INSTRUCTION:
    • Use your unrounded answer from Question 1.
    • Round your answer to two decimal places.
    Answer:

    a= m·s2

    one-of
    type(numeric.abserror(0.01))


ID is: 1467 Seed is: 7644

Applying Newton's second law

Ikenna is pulling a 30 kg box with a rope that makes an angle of 50° with the horizontal.

If he applies a force of magnitude 125 N and a frictional force of magnitude 58,9 N is present, calculate the acceleration of the box.

INSTRUCTION:
  • Round your answer to two decimal places.
  • Use the values for any physical constants you might need, as listed here.
Answer: a= m·s2
one-of
type(numeric.abserror(0.01))

ID is: 1467 Seed is: 6335

Applying Newton's second law

Saymore is pulling a 17 kg box with a rope that makes an angle of 30° with the horizontal.

If he applies a force of magnitude 194 N and a frictional force of magnitude 50,0 N is present, calculate the acceleration of the box.

INSTRUCTION:
  • Round your answer to two decimal places.
  • Use the values for any physical constants you might need, as listed here.
Answer: a= m·s2
one-of
type(numeric.abserror(0.01))


ID is: 4569 Seed is: 8657

Multiple choice: Proportionality with Newton's second law

Adapted from DBE Nov 2015 Grade 11, P1, Q1.3
Physical constants · Physics formulas

A net force with magnitude Fnet is exerted on an object of mass m and it causes an acceleration with a magnitude of a.

If the acceleration experienced by the object is eight times smaller, then the magnitude of the net force that caused this must be ...

A Fnet
B 18Fnet
C 8Fnet
D 164Fnet
Answer:

ID is: 4569 Seed is: 1305

Multiple choice: Proportionality with Newton's second law

Adapted from DBE Nov 2015 Grade 11, P1, Q1.3
Physical constants · Physics formulas

A net force with magnitude Fnet is exerted on an object of mass m and it causes an acceleration with a magnitude of a.

If the acceleration experienced by the object is five times bigger, then the magnitude of the net force that caused this must be ...

A Fnet
B 15Fnet
C 25Fnet
D 5Fnet
Answer:


ID is: 4603 Seed is: 7032

Newton's second law with a helicopter

Adapted from DBE Nov 2016 Grade 11, P1, Q3
Physical constants · Physics formulas

A hovering rescue helicopter has a crate of supplies, with a weight of 2 600 N, hanging from a cable. While the helicopter and crate are stationary, the tension in the cable is 2 770 N.

The winch inside the helicopter starts to accelerate the crate upwards while the helicopter remains in its position. While the crate is being accelerated, the tension in the cable is 2 887 N.

  1. Calculate the mass of the crate.

    INSTRUCTION: Round your answer to two decimal places.
    Answer:

    m=

    one-of
    type(numeric.abserror(0.01))
  2. Calculate the magnitude of the acceleration of the crate.

    INSTRUCTION: Round your answer to two decimal places.
    Answer:

    a=

    one-of
    type(numeric.abserror(0.01))
  3. After it is accelerated for a few metres, the crate is pulled upwards at a constant velocity of 1,59 m·s1. The air resistance associated with its motion is negligible.

    What is the magnitude of the tension in the cable while the crate moves upwards at this constant velocity?

    Answer:

ID is: 4603 Seed is: 4154

Newton's second law with a helicopter

Adapted from DBE Nov 2016 Grade 11, P1, Q3
Physical constants · Physics formulas

A hovering rescue helicopter has a container of supplies, with a weight of 1 850 N, hanging from a cable. While the helicopter and container are stationary, the tension in the cable is 2 010 N.

The winch inside the helicopter starts to pull the container upwards with an acceleration of 1,11 m·s2, while the helicopter remains in its position.

  1. Calculate the mass of the container.

    INSTRUCTION: Round your answer to two decimal places.
    Answer:

    m=

    one-of
    type(numeric.abserror(0.01))
  2. Calculate the magnitude of the tension in the cable while the container is pulled upwards.

    INSTRUCTION: Round your answer to two decimal places.
    Answer:

    T=

    one-of
    type(numeric.abserror(0.01))
  3. After it is accelerated for a few metres, the container is pulled upwards at a constant velocity of 3,99 m·s1. The air resistance associated with its motion is negligible.

    What is the magnitude of the tension in the cable while the container moves upwards at this constant velocity?

    Answer:


ID is: 3837 Seed is: 912

Multiple choice: Newton's second law

Adapted from DBE Feb-Mar 2017 Grade 12, P1, Q1.1
Physical constants · Physics formulas

A group of learners exert the same net force on different objects and cause them to accelerate.

According to Newton's second law of motion, the mass of each object is __________ its acceleration.

A independent of
B inversely proportional to
C always greater than
D directly proportional to
Answer:

ID is: 3837 Seed is: 2100

Multiple choice: Newton's second law

Adapted from DBE Feb-Mar 2017 Grade 12, P1, Q1.1
Physical constants · Physics formulas

A group of learners exert different net forces on a set of objects so that they all have the same acceleration.

According to Newton's second law of motion, the net force experienced by each object is __________ its mass.

A directly proportional to
B inversely proportional to
C always greater than
D independent of
Answer:


ID is: 1469 Seed is: 2416

Forces in a lift

A student experiences a gravitational force of 774,2 N. He gets into a lift and steps onto a bathroom scale that is calibrated in newtons. When the lift is standing still the scale reads 774,2 N. When the student steps into the lift it is on floor 6.

He pushes the button to go to another floor. As the lift moves he notes that the reading on the scale changes during his ride. He records three stages in his journey:

  • Stage 1 For 2 seconds immediately after the lift starts, the scale reads 821,6 N
  • Stage 2 For a further 6 seconds it reads 774,2 N
  • Stage 3 For the final 2 seconds it reads 726,8 N.
  1. Is the acceleration of the lift upward or downward in Stage 1?

    TIP: In a test or exam you will be required to give reasons for your answer.
    Answer:

    The direction of the acceleration in Stage 1 is .

  2. Calculate the resultant force acting on the student during Stage 3.

    INSTRUCTION:
    • Round your answer to one decimal place.
    • Select the direction using the drop-down menu.
    Answer:

    Fnet= N

    one-of
    type(numeric.abserror(0.1))

ID is: 1469 Seed is: 1467

Forces in a lift

A student experiences a gravitational force of 793,8 N. He gets into a lift and steps onto a bathroom scale that is calibrated in newtons. When the lift is standing still the scale reads 793,8 N. When the student steps into the lift it is on floor 4.

He pushes the button to go to another floor. As the lift moves he notes that the reading on the scale changes during his ride. He records three stages in his journey:

  • Stage 1 For 2 seconds immediately after the lift starts, the scale reads 891,0 N
  • Stage 2 For a further 1 seconds it reads 793,8 N
  • Stage 3 For the final 2 seconds it reads 696,6 N.
  1. Is the acceleration of the lift upward or downward in Stage 1?

    TIP: In a test or exam you will be required to give reasons for your answer.
    Answer:

    The direction of the acceleration in Stage 1 is .

  2. Calculate the resultant force acting on the student during Stage 1.

    INSTRUCTION:
    • Round your answer to one decimal place.
    • Select the direction using the drop-down menu.
    Answer:

    Fnet= N

    one-of
    type(numeric.abserror(0.1))


ID is: 3658 Seed is: 5054

Understanding Fnet=ma

The relationship Fnet=ma is a useful equation in mechanics. It is the mathematical statement of Newton's second law of motion.

  1. What does the symbol m stand for?

    Answer:

    The symbol m stands for .

  2. What is the SI unit in which we measure a?

    Answer:

    The SI unit in which we measure a is .


ID is: 3658 Seed is: 9176

Understanding Fnet=ma

The relationship Fnet=ma is a useful equation in mechanics. It is the mathematical statement of Newton's second law of motion.

  1. What does the symbol m represent?

    Answer:

    The symbol m represents .

  2. What is the SI unit in which we measure m?

    Answer:

    The SI unit in which we measure m is .



ID is: 1494 Seed is: 2541

Newton's second law of motion

A tricycle is accelerated at 0,2 m·s2 by a net force of 1,2 N. Calculate the mass of the tricycle.

INSTRUCTION: Round your answer to one decimal place.
Answer: m= kg
one-of
type(numeric.abserror(0.1))

ID is: 1494 Seed is: 4900

Newton's second law of motion

A tricycle has a mass of 4 kg. If a resultant force of 1,2 N is applied to it, what is the magnitude of its acceleration?

INSTRUCTION: Round your answer to one decimal place.
Answer: a= m·s2
one-of
type(numeric.abserror(0.1))


ID is: 3260 Seed is: 9403

Statement: Newton's second law

Adapted from DBE Nov 2015 & 2016 Grade 11, P1, Q4
Physical constants · Physics formulas

State Newton's second law of motion in words.

Answer:

When is applied to a body, the body will the with directly proportional to the magnitude of the net force and the mass of the body.


ID is: 3260 Seed is: 2593

Statement: Newton's second law

Adapted from DBE Nov 2015 & 2016 Grade 11, P1, Q4
Physical constants · Physics formulas

State Newton's second law of motion in words.

Answer:

When acts on a body, the body will in the same direction as the with directly proportional to the magnitude of the and the mass of the body.



ID is: 4568 Seed is: 6723

Multiple choice: Acceleration in a lift

Adapted from DBE Nov 2015 Grade 11, P1, Q1.4
Physical constants · Physics formulas

Aramide has a weight of 860 N. She is in an elevator (a lift) with a bathroom scale that gives a reading in newtons.

At some point while the elevator is getting slower, she looks at the scale and sees a reading of 980 N.

Which one of the following combinations correctly indicates the direction of motion of the elevator and the direction of the acceleration while the elevator is in motion?

Direction of motionDirection of acceleration
A downup
B upup
C updown
D downdown
Answer:

ID is: 4568 Seed is: 9244

Multiple choice: Acceleration in a lift

Adapted from DBE Nov 2015 Grade 11, P1, Q1.4
Physical constants · Physics formulas

Chidi has a weight of 510 N. He is in an elevator (a lift) with a bathroom scale that gives a reading in newtons.

At some point while the elevator is getting faster, he looks at the scale and sees a reading of 550 N.

Which one of the following combinations correctly indicates the direction of motion of the elevator and the direction of the acceleration while the elevator is in motion?

Direction of motionDirection of acceleration
A downdown
B downup
C updown
D upup
Answer:


ID is: 3657 Seed is: 2682

Proportional reasoning with Fnet, m, and a

The relationship Fnet=ma is an important equation in mechanics. It is the mathematical statement of Newton's second law of motion.

  1. For a fixed acceleration, what can we say about the relationship between net force and mass?

    Answer:

    Net force is mass.

  2. Consider the options below and choose the one that represents the relationship between net force and mass symbolically:

    A Fnet=m
    B Fnet>m
    C Fnetm
    D Fnet1m
    E Fnet<m
    Answer:

    The correct option is .

  3. Consider two objects with the same acceleration. The net force of the second object is 7 times smaller than the net force of the first object. How does the mass of the second object compare to the mass of the first object?

    Answer:

    The mass of the second object will be the mass of the first object.


ID is: 3657 Seed is: 8024

Proportional reasoning with Fnet, m, and a

The relationship Fnet=ma is a useful equation in mechanics. It is the mathematical statement of Newton's second law of motion.

  1. For a constant acceleration, what can we say about the relationship between net force and mass?

    Answer:

    Net force is mass.

  2. Consider the options below and choose the one that represents the relationship between net force and mass symbolically:

    A Fnet1m
    B Fnetm
    C Fnet<m
    D Fnet>m
    E Fnet=m
    Answer:

    The correct option is .

  3. Consider two systems with the same acceleration. The net force of the second system is 3 times smaller than the net force of the first system. How does the mass of the second system compare to the mass of the first system?

    Answer:

    The mass of the second system will be the mass of the first system.

9. Equilibrium and non-equilibrium



ID is: 3854 Seed is: 8048

Equilibrium and diagrams

The following free-body diagram (to scale) shows all the forces exerted on an object.

  1. Is the object in equilibrium? Give a reason for your answer.

    Answer:

    The object in equilibrium. We know this because the net force exerted on the object is .


ID is: 3854 Seed is: 594

Equilibrium and diagrams

The following free-body diagram (to scale) shows all the forces exerted on an object.

  1. Is the object in equilibrium? Give a reason for your answer.

    Answer:

    The object in equilibrium. We know this because the net force exerted on the object is .



ID is: 3771 Seed is: 642

MCQ: Unequal forces

An object moving with a constant velocity on a horizontal surface has a number of unequal forces acting on it.

Which one of the following statements must be true?

A The resultant of the forces must be zero.
B Friction balances out the forces acting in the direction of motion.
C At least two of the forces must be acting in opposite directions.
D The resultant force must act in the direction of motion.
Answer:

ID is: 3771 Seed is: 7880

MCQ: Unequal forces

An object moving with a uniform velocity on a horizontal plane has several unequal forces acting on it.

Which one of the following statements must be true?

A The resultant of the forces must be negative.
B The resultant force must act against the direction of motion.
C The resultant of the forces must be zero.
D At least two of the forces must be acting in opposite directions.
Answer:


ID is: 3794 Seed is: 4910

Normal force on an inclined plane

A box is on an inclined plane which forms an angle α with the horizontal. Kungawo pushes the box perpendicularly into the slope with a force F.

    1. How does the magnitude of the normal force (FN) compare to the magnitude of the perpendicular component of the gravitational force (Fg,)?
    2. The magnitudes of the normal force (FN) and the full gravitational force (Fg) have the following relationship:
      A FN>Fg
      B FN<Fg
      C FN=Fg
      D Impossible to determine.
    Answer:
    1. FN is Fg,.
    2. When comparing FN to Fg, the correct relationship is .
  1. Which one of the following is a correct expression for the magnitude of the normal force in this scenario?

    FN= ...

    A FgF
    B Fgcos(α)
    C Fg+F
    D Fg
    E Fgcos(α)+F
    F Fgcos(α)F
    Answer:

    The correct expression is: .


ID is: 3794 Seed is: 1544

Normal force on an inclined plane

A box is on an inclined plane which forms an angle α with the horizontal. Adebanke pulls the box at an angle out of the slope with a force F. The box remains in contact with the surface.

    1. How does the magnitude of the normal force (FN) compare to the magnitude of the perpendicular component of the gravitational force (Fg,)?
    2. The magnitudes of the normal force (FN) and the full gravitational force (Fg) have the following relationship:
      A FN=Fg
      B FN>Fg
      C FN<Fg
      D Impossible to determine.
    Answer:
    1. FN is Fg,.
    2. When comparing FN to Fg, the correct relationship is .
  1. The force F is applied at an angle θ to the slope. Which one of the following is a correct expression for the magnitude of the normal force in this scenario?

    FN= ...

    A Fgcos(α)
    B Fgcos(α)Fsin(θ)
    C Fgcos(α)+Fsin(θ)
    D FgFsin(θ)
    E Fg+Fsin(θ)
    F Fg
    Answer:

    The correct expression is: .



ID is: 4532 Seed is: 8200

Pulleys and vector components

Adapted from DBE Nov 2016 Grade 11, P1, Q2
Physical constants · Physics formulas

A heavy object is lifted using two ropes and two pulleys, as shown in the diagram below. The two pulleys are a distance x apart. The force in Rope A (FA) is 495,2 N and the force in Rope B (FB) is 364,9 N. Rope A makes an angle of 25° with the vertical and Rope B makes an angle of 55° with the horizontal.

  1. Calculate the magnitude of the:

    1. vertical component of FA
    2. horizontal component of FA
    INSTRUCTION: Round your answers to two decimal places.
    Answer:
    1. FA,y=
    2. FA,x=
    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))
  2. Calculate the maximum weight that the two forces can lift.

    INSTRUCTION: Round your answer to two decimal places.
    Answer:

    The maximum weight is .

    one-of
    type(numeric.abserror(0.01))

ID is: 4532 Seed is: 1926

Pulleys and vector components

Adapted from DBE Nov 2016 Grade 11, P1, Q2
Physical constants · Physics formulas

A heavy object is lifted using two ropes and two pulleys, as shown in the diagram below. The two pulleys are a distance x apart. The force in Rope A (FA) is 705,4 N and the force in Rope B (FB) is 614,9 N. Rope A makes an angle of 30° with the vertical and Rope B makes an angle of 55° with the horizontal.

  1. Calculate the magnitude of the:

    1. vertical component of FA
    2. horizontal component of FA
    INSTRUCTION: Round your answers to two decimal places.
    Answer:
    1. FA,y=
    2. FA,x=
    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))
  2. Calculate the maximum weight that the two forces can lift.

    INSTRUCTION: Round your answer to two decimal places.
    Answer:

    The maximum weight is .

    one-of
    type(numeric.abserror(0.01))


ID is: 4598 Seed is: 8371

Multiple choice: The normal force and an applied force at an angle

Adapted from DBE Nov 2016 Grade 11, P1, Q1.2
Physical constants · Physics formulas

Gina pushes a trolley across the ground at constant speed with a force F at an angle of θ from the horizontal. The magnitude of the weight of the trolley is w and the magnitudes of the horizontal and vertical components of the applied pushing force are Fx and Fy respectively.

The magnitude of the frictional force experienced by the object is ...

A Fy
B Fx
C w
D FN
Answer:

ID is: 4598 Seed is: 6348

Multiple choice: The normal force and an applied force at an angle

Adapted from DBE Nov 2016 Grade 11, P1, Q1.2
Physical constants · Physics formulas

Kungawo pushes a trolley across the ground at constant speed with a force F at an angle of θ from the horizontal. The magnitude of the weight of the trolley is w and the magnitudes of the horizontal and vertical components of the applied pushing force are Fx and Fy respectively.

The magnitude of the normal force experienced by the object is ...

A w+Fx
B w+Fy
C wFy
D w
Answer:


ID is: 3857 Seed is: 1183

Match the scenario to a free-body diagram

Consider the following scenario and answer the questions that follow.

Moselantja connects an object to a light inextensible rope which is run over a light frictionless pulley. Moselantja pulls on the rope, and the object accelerates up.

  1. Is the object in equilibrium? If it is in equilibrium, what type of equilibrium? Give a reason for your answer.

    Answer:

    The object is equilibrium. We know this because it so the net force exerted on the object must be .

  2. Which one of the following is the correct free-body diagram for the object?

    TIP: Pay careful attention to scale. How long should the force vectors be compared to each other?
    A
    B
    C
    Answer:

    The correct diagram is:


ID is: 3857 Seed is: 3726

Match the scenario to a free-body diagram

Consider the following scenario and answer the questions that follow.

Lindiwe uses a rope to hang a charged insulated sphere from the ceiling. An electrostatic force pulls the charged sphere to the left. The sphere hangs without moving in the position shown in the diagram below.

  1. Is the charged sphere in equilibrium? If it is in equilibrium, what type of equilibrium? Give a reason for your answer.

    Answer:

    The charged sphere is equilibrium. We know this because it so the net force exerted on the charged sphere must be .

  2. Which one of the following is the correct free-body diagram for the charged sphere?

    TIP: Pay careful attention to scale. How long should the force vectors be compared to each other?
    A
    B
    C
    Answer:

    The correct diagram is:



ID is: 1495 Seed is: 2786

Resultant force

A donkey is trying to pull a cart with a constant force of 399 N. The cart experiences a force due to gravity of 2 075 N. The rope between the cart and the donkey makes an angle of 26° to the horizontal. The cart does not move.

Find the magnitude and direction of the frictional force preventing the cart from moving.

INSTRUCTION: Round your answer to two decimal places.
Answer:

Ffriction= N

one-of
type(numeric.abserror(0.01))

ID is: 1495 Seed is: 7753

Resultant force

An ox is trying to pull a cart with a constant force of 275 N. The cart experiences a force due to gravity of 2 347 N. The rope between the cart and the ox makes an angle of 20° to the horizontal. The cart does not move.

Find the magnitude and direction of the frictional force preventing the cart from moving.

INSTRUCTION: Round your answer to two decimal places.
Answer:

Ffriction= N

one-of
type(numeric.abserror(0.01))


ID is: 1547 Seed is: 5918

Components of forces

A block that experiences a gravitational force of 519,4 N is placed on a slope that makes an angle of 44° with the horizontal. The block does not slide down the slope. Calculate the magnitude and direction of the frictional force and the normal force present in this situation.

INSTRUCTION: Round your answers to two decimal places.
Answer:

fs= N
FN= N

one-of
type(numeric.abserror(0.01))
one-of
type(numeric.abserror(0.01))

ID is: 1547 Seed is: 1862

Components of forces

A block that experiences a gravitational force of 931,0 N is placed on a slope that makes an angle of 42° with the horizontal. The block does not slide down the slope. Calculate the magnitude and direction of the frictional force and the normal force present in this situation.

INSTRUCTION: Round your answers to two decimal places.
Answer:

fs= N
FN= N

one-of
type(numeric.abserror(0.01))
one-of
type(numeric.abserror(0.01))


ID is: 3792 Seed is: 1008

Match the scenario to a force diagram

Consider the following scenario and answer the questions that follow.

Yaseen exerts a pushing force on a block up a rough slope, but the block remains at rest.

TIP: The surface is rough. This is a clue that friction cannot be ignored in this problem!
  1. Is the block in equilibrium? If it is in equilibrium, what type of equilibrium? Give a reason for your answer.

    Answer:

    The block is equilibrium. We know this because it so the net force exerted on the block must be .

  2. Which one of the following is the correct force diagram for the block?

    TIP: Pay careful attention to scale. How long should the force vectors be compared to each other?
    A
    B
    C
    Answer:

    The correct diagram is:


ID is: 3792 Seed is: 1889

Match the scenario to a force diagram

Consider the following scenario and answer the questions that follow.

Langa drops a ball from rest from the roof of a tall building. Once the ball leaves contact with Langa's hand it accelerates downwards. While falling the ball experiences both the gravitational force and air resistance.

  1. Is the ball in equilibrium? If it is in equilibrium, what type of equilibrium? Give a reason for your answer.

    Answer:

    The ball is equilibrium. We know this because it so the net force exerted on the ball must be .

  2. Which one of the following is the correct force diagram for the ball?

    TIP: Pay careful attention to scale. How long should the force vectors be compared to each other?
    A
    B
    C
    Answer:

    The correct diagram is:



ID is: 3811 Seed is: 4410

Normal force on a horizontal surface

An object is on a horizontal surface. Joshua pulls the object straight up with a force F. The object remains in contact with the surface.

How does the magnitude of the normal force (FN) compare to the magnitude of the gravitational force (Fg)?

Answer:

FN is Fg.


ID is: 3811 Seed is: 7611

Normal force on a horizontal surface

A crate is on a horizontal surface. Abidemi pulls the crate at an angle out of the surface with a force F. The crate remains in contact with the surface.

How does the magnitude of the normal force (FN) compare to the magnitude of the gravitational force (Fg)?

Answer:

FN is Fg.



ID is: 3616 Seed is: 2717

Multiple choice: Vertical systems

A block of mass m1 is connected to another block of mass m2 by a light inextensible rope. This system of blocks is then suspended from the ceiling by the top block, using the same type of rope.

  1. The hanging system of blocks is in static equilibrium. What does this mean?

    A The system only experiences electrostatic forces.
    B The acceleration and velocity of the system are both zero.
    C The system is stationary because it experiences the static frictional force.
    D The Newton's third law action-reaction pairs all cancel each other out.
    Answer:

    The correct statement is .


ID is: 3616 Seed is: 761

Multiple choice: Vertical systems

A block of mass m1 is connected to another block of mass m2 by a light inextensible string. This system of blocks is then suspended from the ceiling by the top block, using the same type of string.

  1. The hanging system of blocks is in static equilibrium. What does this mean?

    A The system gently swings from side to side.
    B The Newton's third law action-reaction pairs all cancel each other out.
    C The system only experiences electrostatic forces.
    D The net force experienced by the system is zero and the system does not move.
    Answer:

    The correct statement is .



ID is: 3856 Seed is: 2763

Types of equilibrium

Consider the following scenario and answer the questions that follow.

Adebisi places a package in a lift which moves down at a constant velocity.

Is the package in equilibrium? If it is in equilibrium, what type of equilibrium? Give a reason for your answer.

Answer:

The package is equilibrium. We know this because it so the net force exerted on the package must be .


ID is: 3856 Seed is: 7116

Types of equilibrium

Consider the following scenario and answer the questions that follow.

Abidemi throws a ball downwards from the roof of a tall building. Once the ball leaves contact with Abidemi's hand it accelerates downwards. While falling the ball experiences both the gravitational force and air resistance.

Is the ball in equilibrium? If it is in equilibrium, what type of equilibrium? Give a reason for your answer.

Answer:

The ball is equilibrium. We know this because it so the net force exerted on the ball must be .



ID is: 3855 Seed is: 7665

Match the free-body diagram to a scenario

The following free-body diagram (to scale) shows all the forces exerted on an object.

  1. Is the object in equilibrium? Give a reason for your answer.

    Answer:

    The object in equilibrium. We know this because the net force exerted on the object is .

  2. Which one of the following scenarios contains an object that could be described by the given free-body diagram?

    A Rethabile exerts a pulling force to the right on a box on a smooth horizontal surface, and the box accelerates to the right.
    B Rethabile places a box in a lift which accelerates down.
    C Rethabile connects a box to a light inextensible rope which is run over a frictionless pulley. Rethabile pulls on the rope, but the box hangs motionless.
    D Rethabile drops a ball from rest from the roof of a tall building. Once the ball leaves contact with Rethabile's hand it accelerates downwards. While falling the ball experiences only the gravitational force.
    Answer:

    The correct scenario is:


ID is: 3855 Seed is: 6486

Match the free-body diagram to a scenario

The following free-body diagram (to scale) shows all the forces exerted on an object.

  1. Is the object in equilibrium? Give a reason for your answer.

    Answer:

    The object in equilibrium. We know this because the net force exerted on the object is .

  2. Which one of the following scenarios contains an object that could be described by the given free-body diagram?

    A Tanya throws a ball upwards from the roof of a tall building. Once the ball leaves contact with Tanya's hand it moves up, while being slowed down by the gravitational force only.
    B Tanya exerts a pulling force to the right on a box on a rough horizontal surface, and the box slides across the surface at a constant velocity.
    C Tanya places a box in a lift which accelerates down.
    D Tanya exerts a pulling force to the right on a system of two boxes on a smooth horizontal surface, and the system accelerates to the right.
    Answer:

    The correct scenario is:



ID is: 4534 Seed is: 5821

The distance between pulleys

Adapted from DBE Nov 2016 Grade 11, P1, Q2
Physical constants · Physics formulas

A heavy object is lifted upwards with a constant velocity using two ropes and two pulleys, as shown in the diagram below. The two pulleys are a distance x apart. The force in Rope A (FA) is 477,2 N and the force in Rope B (FB) is 547,4 N. Rope A makes an angle of 55° with the horizontal and Rope B makes an angle of 30° with the vertical.

The distance x between the centres of the pulleys is decreased. Will the pulley system be more or less effective? Give a reason for your answer.

Answer:

The pulley system will be effective. This is because:


ID is: 4534 Seed is: 4994

The distance between pulleys

Adapted from DBE Nov 2016 Grade 11, P1, Q2
Physical constants · Physics formulas

A heavy object is accelerated upwards using two ropes and two pulleys, as shown in the diagram below. The two pulleys are a distance x apart. The force in Rope A (FA) is 673 N and the force in Rope B (FB) is 831,6 N. Rope A makes an angle of 25° with the vertical and Rope B makes an angle of 70° with the horizontal.

The distance x between the centres of the pulleys is decreased. Will the pulley system be more or less effective? Give a reason for your answer.

Answer:

The pulley system will be effective. This is because:



ID is: 3791 Seed is: 9231

Normal force on a horizontal surface

An object is on a horizontal surface. Kungawo pushes the object at an angle into the surface with a force F.

  1. How does the magnitude of the normal force (FN) compare to the magnitude of the gravitational force (Fg)?

    Answer:

    FN is Fg.

  2. The force F is applied at an angle θ to the horizontal. Which one of the following is a correct expression for the magnitude of the normal force in this scenario?

    FN= ...

    A Fg
    B Fg+Fsin(θ)
    C FgF
    D FgFsin(θ)
    E Fg+F
    Answer:

    The correct expression is: .


ID is: 3791 Seed is: 1811

Normal force on a horizontal surface

An object is on a horizontal surface. Jezile pushes the object at an angle into the surface with a force F.

  1. How does the magnitude of the normal force (FN) compare to the magnitude of the gravitational force (Fg)?

    Answer:

    FN is Fg.

  2. The force F is applied at an angle θ to the horizontal. Which one of the following is a correct expression for the magnitude of the normal force in this scenario?

    FN= ...

    A Fg+Fsin(θ)
    B FgFsin(θ)
    C Fg+F
    D FgF
    E Fg
    Answer:

    The correct expression is: .



ID is: 3812 Seed is: 9949

Normal force on an inclined plane

A crate is on an inclined plane which forms an angle α with the horizontal. Anita pulls the crate at an angle out of the slope with a force F. The crate remains in contact with the surface.

  1. How does the magnitude of the normal force (FN) compare to the magnitude of the perpendicular component of the gravitational force (Fg,)?
  2. The magnitudes of the normal force (FN) and the full gravitational force (Fg) have the following relationship:
    A FN<Fg
    B FN=Fg
    C FN>Fg
    D Impossible to determine.
Answer:
  1. FN is Fg,.
  2. When comparing FN to Fg, the correct relationship is .

ID is: 3812 Seed is: 3793

Normal force on an inclined plane

A crate is on an inclined plane which forms an angle α with the horizontal. Ntombikanina pushes the crate at an angle into the slope with a force F.

  1. How does the magnitude of the normal force (FN) compare to the magnitude of the perpendicular component of the gravitational force (Fg,)?
  2. The magnitudes of the normal force (FN) and the full gravitational force (Fg) have the following relationship:
    A FN=Fg
    B FN<Fg
    C FN>Fg
    D Impossible to determine.
Answer:
  1. FN is Fg,.
  2. When comparing FN to Fg, the correct relationship is .


ID is: 4533 Seed is: 8803

Closed and open vector diagrams

Adapted from DBE Nov 2016 Grade 11, P1, Q2
Physical constants · Physics formulas

A heavy object is accelerated upwards using two ropes and two pulleys, as shown in the diagram below. The two pulleys are a distance x apart. The force in Rope A (FA) is 773,5 N and the force in Rope B (FB) is 915,1 N. Rope A makes an angle of 60° with the horizontal and Rope B makes an angle of 25° with the vertical.

Will the vector diagram of Force FA, Force FB, and the weight of the object be closed or open? Give a reason for your answer.

Answer:

The vector diagram will be . This is because:


ID is: 4533 Seed is: 9675

Closed and open vector diagrams

Adapted from DBE Nov 2016 Grade 11, P1, Q2
Physical constants · Physics formulas

A heavy object is accelerated upwards using two ropes and two pulleys, as shown in the diagram below. The two pulleys are a distance x apart. The force in Rope A (FA) is 386 N and the force in Rope B (FB) is 344,4 N. Rope A makes an angle of 35° with the vertical and Rope B makes an angle of 50° with the horizontal.

Will the vector diagram of Force FA, Force FB, and the weight of the object be closed or open? Give a reason for your answer.

Answer:

The vector diagram will be . This is because:



ID is: 3772 Seed is: 4869

MCQ: Free-body diagrams

Bridget is driving a truck along a straight horizontal road to the east.

The truck is travelling at a constant speed of 70 km·h1. Which one of the following free-body diagrams best represents all the forces acting on Bridget and the truck?

A
B
C
D
Answer:

ID is: 3772 Seed is: 6370

MCQ: Free-body diagrams

Bridget is travelling in a train along a straight horizontal track to the right.

The train is travelling at a constant speed of 80 km·h1. Which one of the following free-body diagrams best represents all the forces acting on Bridget and the train?

A
B
C
D
Answer:


ID is: 4617 Seed is: 6502

Multiple choice: Action-reaction pairs

Adapted from DBE Nov 2016 Grade 11, P1, Q1.3
Physical constants · Physics formulas

A donkey is trying to pull a wagon with no wheels across a rough dirt path, but the wagon will not move.

One of the forces experienced by the wagon is the static frictional force, fs. The force that forms an action-reaction pair with the static frictional force experienced by the wagon is the force of the ...

A wagon on the donkey.
B donkey on the path.
C wagon on the path.
D path on the donkey.
Answer:

ID is: 4617 Seed is: 7057

Multiple choice: Action-reaction pairs

Adapted from DBE Nov 2016 Grade 11, P1, Q1.3
Physical constants · Physics formulas

A magnet is stuck to a fridge.

One of the forces experienced by the magnet is the magnetic force, Fmag. The force that forms an action-reaction pair with the magnetic force experienced by the magnet is the force of the ...

A fridge on the Earth.
B Earth on the magnet.
C magnet on the fridge.
D magnet on the Earth.
Answer:


ID is: 4602 Seed is: 8298

Forces and a hovering helicopter

Adapted from DBE Nov 2016 Grade 11, P1, Q3
Physical constants · Physics formulas

A hovering rescue helicopter has a container of supplies, with a weight of 2 560 N, hanging from a cable. The tension in the cable is 2 700 N.

  1. Why does the container remain stationary despite the tension being greater than the weight?
  2. Draw a labelled force diagram showing all of the forces acting on the container of supplies to support your answer. Then describe your force diagram.
Answer:

1.

2.

  • Number of forces acting up:
  • Number of forces acting down:
  • The force vectors equal in size.

ID is: 4602 Seed is: 3044

Forces and a hovering helicopter

Adapted from DBE Nov 2016 Grade 11, P1, Q3
Physical constants · Physics formulas

A hovering rescue helicopter has a container of supplies, with a weight of 2 009 N, hanging from a cable. The tension in the cable is 2 160 N.

  1. Why does the container remain stationary despite the tension being greater than the weight?
  2. Draw a labelled force diagram showing all of the forces acting on the container of supplies to support your answer. Then describe your force diagram.
Answer:

1.

2.

  • Number of forces acting up:
  • Number of forces acting down:
  • The force vectors equal in size.


ID is: 4567 Seed is: 3147

Equilibrium on a rough horizontal surface

Adapted from DBE Nov 2015 Grade 11, P1, Q3
Physical constants · Physics formulas

A 50 kg block is placed on a rough horizontal surface. A constant force (F) pushes the block and the block moves across the surface at a constant speed as shown in the diagram below. The coefficient of kinetic friction (μk) between the block and the surface is 0,58.

  1. Calculate the magnitudes of:

    1. Force F.
    2. The normal force acting on the block.
    INSTRUCTION: Round your answers to two decimal places.
    Answer:
    1. F=
    2. FN=
    numeric
    numeric
  2. Calculate the magnitude of the kinetic frictional force.

    INSTRUCTION: Round your answer to two decimal places.
    Answer:

    fk=

    numeric

ID is: 4567 Seed is: 7078

Equilibrium on a rough horizontal surface

Adapted from DBE Nov 2015 Grade 11, P1, Q3
Physical constants · Physics formulas

A 20 kg block is placed on a rough horizontal surface. A constant force (F) pushes the block and the block moves across the surface at a constant speed as shown in the diagram below. The coefficient of kinetic friction (μk) between the block and the surface is 0,42.

  1. Calculate the magnitudes of:

    1. Force F.
    2. The normal force acting on the block.
    INSTRUCTION: Round your answers to two decimal places.
    Answer:
    1. F=
    2. FN=
    numeric
    numeric
  2. Calculate the magnitude of the kinetic frictional force.

    INSTRUCTION: Round your answer to two decimal places.
    Answer:

    fk=

    numeric

10. Systems and pulleys



ID is: 4618 Seed is: 821

A pulley with an equation of motion

Adapted from DBE Nov 2015 Grade 11, P1, Q4.2
Physical constants · Physics formulas

In the diagram below, a 6 kg mass and a 10 kg mass are connected by an inextensible string of negligible mass. The string is passed over a light, frictionless pulley so that the masses hang down as shown. Initially the system is held stationary.

All forms of friction and air resistance can be ignored.

Calculate the speed of the 6 kg mass 0,74 s after it is released. You can assume that the string is long enough and neither mass reaches the pulley.

INSTRUCTION: Round your answer to two decimal places.
Answer:

vf=

one-of
type(numeric.abserror(0.01))

ID is: 4618 Seed is: 5777

A pulley with an equation of motion

Adapted from DBE Nov 2015 Grade 11, P1, Q4.2
Physical constants · Physics formulas

In the diagram below, a 4 kg mass and a 2 kg mass are connected by an inextensible string of negligible mass. The string is passed over a light, frictionless pulley so that the masses hang down as shown. Initially the system is held stationary.

All forms of friction and air resistance can be ignored.

Calculate the amount of time it will take the 4 kg mass to move a distance of 1,19 m after the system is released. You can assume that the string is long enough and neither mass reaches the pulley.

INSTRUCTION: Round your answer to two decimal places.
Answer:

Δt=

one-of
type(numeric.abserror(0.01))


ID is: 4623 Seed is: 7020

Two blocks on a rough slope

Adapted from DBE Nov 2015 Grade 11, P1, Q4.1
Physical constants · Physics formulas

Two heavy wooden blocks of mass 30 kg and 15 kg respectively are placed on a rough slope inclined at an angle of 14° to the horizontal. The blocks are connected to each other by a light inextensible cable. The sides of the blocks which touch the inclined slope have the same area.

A man pulls on the top block with a force of 260 N, via the cable, and the system of blocks accelerates up the slope. The 30 kg block experiences a kinetic frictional force of 82 N and the 15 kg block experiences a kinetic frictional force of 41 N.

  1. Draw a free-body diagram showing all forces acting on the 30 kg block (the bottom block). Then use your free-body diagram to answer the following questions about the 30 kg block.

    1. How many forces are in the free-body diagram?
    2. In which direction does the tensional force act?
    3. In which direction does the frictional force act?
    4. Does the man exert a force on this block?
    Answer:

    For the bottom block:

    1. There is/are force(s) in the free-body diagram.
    2. The tensional force acts .
    3. The frictional force acts .
    4. The man exert a force on this block.
    one-of
    type(string.nocase)
  2. Calculate the:

    1. magnitude of the acceleration of the system of blocks.
    2. magnitude of the tensional force in the cable between the blocks.
    INSTRUCTION: Round your answers to two decimal places.
    Answer:
    1. a=
    2. T=
    one-of
    type(numeric.abserror(0.01))
    numeric

ID is: 4623 Seed is: 6651

Two blocks on a rough slope

Adapted from DBE Nov 2015 Grade 11, P1, Q4.1
Physical constants · Physics formulas

Two heavy wooden crates of mass 13 kg and 26 kg respectively are placed on a rough slope inclined at an angle of 14° to the horizontal. The crates are connected to each other by a light inextensible cable. The sides of the crates which touch the inclined slope have the same area.

A man pulls on the top crate with a force of 200 N, via the cable, and the system of crates accelerates up the slope. The 13 kg crate experiences a kinetic frictional force of 27 N and the 26 kg crate experiences a kinetic frictional force of 54 N.

  1. Draw a free-body diagram showing all forces acting on the 26 kg crate (the top crate). Then use your free-body diagram to answer the following questions about the 26 kg crate.

    1. How many forces are in the free-body diagram?
    2. In which direction does the tensional force act?
    3. In which direction does the frictional force act?
    4. Does the man exert a force on this crate?
    Answer:

    For the top crate:

    1. There is/are force(s) in the free-body diagram.
    2. The tensional force acts .
    3. The frictional force acts .
    4. The man exert a force on this crate.
    one-of
    type(string.nocase)
  2. Calculate the:

    1. magnitude of the acceleration of the system of crates.
    2. magnitude of the tensional force in the cable between the crates.
    INSTRUCTION: Round your answers to two decimal places.
    Answer:
    1. a=
    2. T=
    one-of
    type(numeric.abserror(0.01))
    numeric


ID is: 3668 Seed is: 6309

Systems on rough inclined planes

A crate of mass 9 kg is connected to another crate of mass 3 kg by a light inextensible string. The system is pulled up a rough plane inclined at 42° to the horizontal, by means of a constant 110 N force parallel to the plane as shown in the diagram below.

The crates are not made from the same material. The magnitude of the kinetic frictional force between the surface and the 3 kg crate is 4,59 N. The coefficient of kinetic friction between the 9 kg crate and the surface is 0,21.

  1. Draw a labelled free-body diagram indicating all the forces acting on the 9 kg crate as it moves up the plane.

    Compare your diagram to the diagram given below. Is the given diagram correct? Choose a reason for your answer from the options provided.

    1 all forces are included and point in the correct direction
    2 there is a normal force in the diagram
    3 the gravitational force in the diagram points down
    4 there is no kinetic frictional force in the diagram
    Answer:

    The given diagram . This is because .

  2. Calculate the magnitude of the:

    1. Kinetic frictional force between the 9 kg crate and the surface of the plane.
    2. Tension in the string connecting the two crates.
    INSTRUCTIONS:
    • Round both of your final answers to two decimal places.
    • Use the values given here for any physical constants that you may need.
    Answer:

    fk,1=

    T=

    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))

ID is: 3668 Seed is: 5645

Systems on rough inclined planes

A box of mass 2 kg is connected to another box of mass 8 kg by a light inextensible rope. The system is pulled up a rough plane inclined at 42° to the horizontal, by means of a constant 90 N force parallel to the plane as shown in the diagram below.

The boxes are not made from the same material. The magnitude of the kinetic frictional force between the surface and the 8 kg box is 20,39 N. The coefficient of kinetic friction between the 2 kg box and the surface is 0,35.

  1. Draw a labelled free-body diagram showing all the forces acting on the 2 kg box as it moves up the plane.

    Compare your diagram to the diagram given below. Is the given diagram correct? Choose a reason for your answer from the options provided.

    1 the gravitational force in the diagram points perpendicularly into the plane
    2 there is a normal force in the diagram
    3 there is a kinetic frictional force in the diagram
    4 all forces are included and point in the correct direction
    Answer:

    The given diagram . This is because .

  2. Calculate the magnitude of the:

    1. Kinetic frictional force between the 2 kg box and the surface of the plane.
    2. Tension in the rope connecting the two boxes.
    INSTRUCTIONS:
    • Round both of your final answers to two decimal places.
    • Use the values given here for any physical constants that you may need.
    Answer:

    fk,1=

    T=

    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))


ID is: 3215 Seed is: 6096

Two pulleys with a crate on a frictionless surface

A crate of mass 17,5 kg is on a smooth horizontal table. Two mass pieces of masses 2,1 kg and 1,7 kg are attached to the crate via two light inextensible strings which are passed over massless and frictionless pulleys as shown in the diagram below.

Calculate the acceleration of the crate as well as the magnitudes of the tension in each string.

INSTRUCTION:
  • Round all of your answers to two decimal places.
  • You must use these values for any physical constants that you might need.
Answer:

a= m·s2
T1= N
T2= N

one-of
type(numeric.abserror(0.01))
one-of
type(numeric.abserror(0.01))
one-of
type(numeric.abserror(0.01))

ID is: 3215 Seed is: 4226

Two pulleys with a box on a frictionless surface

A box of mass 17,1 kg is on a smooth horizontal table. Two mass pieces of masses 2,9 kg and 1,6 kg are attached to the box via two light inextensible strings which are passed over massless and frictionless pulleys as shown in the diagram below.

Determine the acceleration of Mass 2 as well as the magnitudes of the tension in each string.

INSTRUCTION:
  • Round all of your answers to two decimal places.
  • You must use these values for any physical constants that you might need.
Answer:

a= m·s2
T1= N
T2= N

one-of
type(numeric.abserror(0.01))
one-of
type(numeric.abserror(0.01))
one-of
type(numeric.abserror(0.01))


ID is: 1468 Seed is: 3599

Newton's second law

A 2 100 kg bus pulls a 1 130 kg trailer with a constant acceleration. The tow bar between the bus and trailer makes an angle 20° degrees with the horizontal. The engine of the bus produces a thrust of 10 000 N.

Calculate the magnitude of the tension T between the bus and the trailer, and the magnitude of the acceleration a of the bus. Ignore the effects of friction.

INSTRUCTION: Round your answers to two decimal places.
Answer:

T= N

a= m·s2

one-of
type(numeric.abserror(0.01))
one-of
type(numeric.abserror(0.01))

ID is: 1468 Seed is: 5481

Newton's second law

A 2 300 kg truck pulls a 1 490 kg trailer with a constant acceleration. The tow bar between the truck and trailer makes an angle 35° degrees with the horizontal. The engine of the truck produces a thrust of 12 000 N.

Calculate the magnitude of the tension T between the truck and the trailer, and the magnitude of the acceleration a of the truck. Ignore the effects of friction.

INSTRUCTION: Round your answers to two decimal places.
Answer:

T= N

a= m·s2

one-of
type(numeric.abserror(0.01))
one-of
type(numeric.abserror(0.01))


ID is: 3238 Seed is: 7521

Tension and pulleys

Two blocks of masses 25 kg and 40 kg are connected by a light inextensible string, R. A second light inextensible string, S, attached to the 40 kg block, runs over a light frictionless pulley. A constant horizontal force of 520 N pulls string S as shown in the diagram below. The magnitudes of the tensions in R and S are T1 and T2 respectively. Ignore the effects of air friction.

  1. Which one of following diagrams is a correctly labelled free-body diagram indicating all the forces acting on the the 40 kg block?

    A
    B
    C
    D
    Answer:

    The correct diagram is:

  2. Calculate the magnitude of the tension T1 in String R as well as the acceleration of the 40 kg block.

    INSTRUCTIONS:
    • Round both of your final answers to two decimal places.
    • You must use these values for any physical constants that you might need.
    Answer:

    T1=
    a=

    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))
  3. When the 520 N force is replaced by a sharp tug on the string, one of the two strings will break.

    Which one of the two strings, R or S, will break?

    Answer:

    String will break.


ID is: 3238 Seed is: 8987

Tension and pulleys

Two blocks of masses 10 kg and 30 kg are connected by a light inextensible string, J. A second light inextensible string, K, attached to the 30 kg block, runs over a light frictionless pulley. A constant horizontal force of 350 N pulls string K as shown in the diagram below. The magnitudes of the tensions in J and K are T1 and T2 respectively. Ignore the effects of air friction.

  1. Which one of following diagrams is a correctly labelled force diagram indicating all the forces acting on the the 30 kg block?

    A
    B
    C
    D
    Answer:

    The correct diagram is:

  2. Calculate the magnitude of the tension T1 in String J as well as the acceleration of the 30 kg block.

    INSTRUCTIONS:
    • Round both of your final answers to two decimal places.
    • You must use these values for any physical constants that you might need.
    Answer:

    T1=
    a=

    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))
  3. When the 350 N force is replaced by a sharp tug on the string, one of the two strings will snap.

    Which one of the two strings, J or K, will snap?

    Answer:

    String will snap.



ID is: 3613 Seed is: 8951

Hanging blocks

A block of mass 3,1 kg is connected to another block of mass 3,8 kg by a light inextensible cable. This system of blocks is then suspended from the ceiling by the top block, using the same type of cable.

  1. Calculate the magnitude of the tensional force in each string.

    INSTRUCTIONS:
    • Do not round any values from intermediate steps.
    • Round both of your final answers to one decimal place.
    • You must use these values for any physical constants that you might need.
    Answer:

    T1=

    T2=

    one-of
    type(numeric.abserror(0.1))
    one-of
    type(numeric.abserror(0.1))
  2. Imagine that the entire system is moved to Ariel (a moon of Uranus) which has a gravitational acceleration of 2,62×107 m·s2.

    What effect will this have on:

    1. the mass of the bottom block?
    2. the tension in the cable connecting the two blocks ?
    Answer:
    1. The mass of the bottom block will .
    2. The tension in the cable connecting the two blocks will .

ID is: 3613 Seed is: 2528

Hanging blocks

A block of mass 9,0 kg is connected to another block of mass 9,9 kg by a light inextensible rope. This system of blocks is then suspended from the ceiling by the top block, using the same type of rope.

  1. Calculate the magnitude of the tensional force in each string.

    INSTRUCTIONS:
    • Do not round any values from intermediate steps.
    • Round both of your final answers to one decimal place.
    • You must use these values for any physical constants that you might need.
    Answer:

    T1=

    T2=

    one-of
    type(numeric.abserror(0.1))
    one-of
    type(numeric.abserror(0.1))
  2. Imagine that the entire system is moved to Venus (a planet) which has a gravitational acceleration of 8,65×106 m·s2.

    What effect will this have on:

    1. the mass of the top block?
    2. the tension in the rope connecting the top block to the ceiling ?
    Answer:
    1. The mass of the top block will .
    2. The tension in the rope connecting the top block to the ceiling will .


ID is: 3678 Seed is: 9085

Dog sledding

A team of dogs pulls two dog sleds across a frozen pond. The sled at the front has an unknown mass m2 and the sled at the back has a mass of 150 kg. The ropes attached to the dogs form an angle of 17° with the horizontal and the dogs pull with a constant force of 270 N.

While the sleds are being pulled, the front sled experiences a normal force of 730 N and the tension in the horizontal rope connecting the two sleds is T. All forms of friction can be ignored.

NOTE:

A sled is used for transport. It either has a flat bottom or long, thin strips of metal or wood attached to the bottom. A dog sled is pulled by one or more dogs (often huskies) and is used to move over ice and through snow. There are many different types of dog sled, with some being used for transport and others being used for racing.

  1. Draw labelled free-body diagrams showing all the forces acting on both of the sleds as they are pulled by the dogs. Compare your diagrams to the two diagrams given below.

    For each of the forces labelled X, Y, and Z indicate:

    • the type of force represented.
    • which sled experiences the force.
    Answer:

    X is the force on the sled

    Y is the force on the sled

    Z is the force on the sled

  2. Calculate the mass of the front sled, m2.

    INSTRUCTIONS:
    • Round your answer to one decimal place.
    • Use the values given here for any physical constants that you may need.
    Answer:

    m2=

    one-of
    type(numeric.abserror(0.1))
  3. Calculate the acceleration of the sleds as well as the tension in the rope connecting the two sleds.

    INSTRUCTION:
    • Round both of your final answers to two decimal places.
    • Where appropriate, use unrounded answers from previous calculations.
    • Use the values given here for any physical constants that you may need.
    Answer:

    a=

    T=

    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))

ID is: 3678 Seed is: 8595

Dog sledding

A team of dogs pulls two dog sleds across a frozen pond. The sled at the front has an unknown mass m2 and the sled at the back has a mass of 110 kg. The ropes attached to the dogs form an angle of 10° with the horizontal and the dogs pull with a constant force of 310 N.

While the sleds are being pulled, the front sled experiences a normal force of 890 N and the tension in the horizontal rope connecting the two sleds is T. All forms of friction can be ignored.

NOTE:

A sled is used for transport. It either has a flat bottom or long, thin strips of metal or wood attached to the bottom. A dog sled is pulled by one or more dogs (often huskies) and is used to move over ice and through snow. There are many different types of dog sled, with some being used for transport and others being used for racing.

  1. Draw labelled free-body diagrams representing all the forces acting on both of the sleds as they are pulled by the dogs. Compare your diagrams to the two diagrams given below.

    For each of the forces labelled X, Y, and Z indicate:

    • the type of force represented.
    • which sled experiences the force.
    Answer:

    X is the force on the sled

    Y is the force on the sled

    Z is the force on the sled

  2. Calculate the mass of the front sled, m2.

    INSTRUCTIONS:
    • Round your answer to one decimal place.
    • Use the values given here for any physical constants that you may need.
    Answer:

    m2=

    one-of
    type(numeric.abserror(0.1))
  3. Calculate the acceleration of the sleds as well as the tension in the rope connecting the two sleds.

    INSTRUCTION:
    • Round both of your final answers to two decimal places.
    • Where appropriate, use unrounded answers from previous calculations.
    • Use the values given here for any physical constants that you may need.
    Answer:

    a=

    T=

    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))


ID is: 3672 Seed is: 9243

Systems on smooth inclined planes

A box of mass 7,5 kg is connected to another box of mass 8,8 kg by a light inextensible string. The same type of string is attached to the 8,8 kg box, run over a light frictionless pulley, and connected to a motor.

The motor pulls the system up a smooth plane inclined at an angle α to the horizontal. The motor applies a constant force of 150 N which causes the system to accelerate at 2,3 m·s2. The force applied by the motor is parallel to the plane as shown in the diagram below. Ignore all forms of friction.

  1. Draw a labelled free-body diagram indicating all the forces acting on the 7,5 kg box.

    How many forces should there be in this diagram?Remember that a free-body diagram should contain actual forces, not components of forces.

    Answer:

    There is/are force(s) in the free-body diagram for the 7,5 kg box.

    one-of
    type(string)
  2. Here is the diagram again:

    Which one of the following expressions is equal to the magnitude of the net force experienced by the 7,5 kg box?

    TIP: Note that the angle is given to the horizontal!
    Answer:
  3. Here is the diagram again:

    Calculate the tension (T) in the string connecting the two boxes as well as the angle (α).

    INSTRUCTIONS:
    • Do not round any values from intermediate steps.
    • Round both of your final answers to two decimal places.
    • Use the values given here for any physical constants that you may need.
    Answer:

    T=

    α = °

    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))

ID is: 3672 Seed is: 587

Systems on smooth inclined planes

A crate of mass 3,1 kg is connected to another crate of mass 7,2 kg by a light inextensible cable. The same type of cable is attached to the 7,2 kg crate, run over a light frictionless pulley, and connected to a motor.

The motor pulls the system up a smooth plane inclined at an angle α to the horizontal. The motor applies a constant force of 70 N which causes the system to accelerate at 0,76 m·s2. The force applied by the motor is parallel to the plane as shown in the diagram below. Ignore all forms of friction.

  1. Draw a labelled free-body diagram representing all the forces acting on the 7,2 kg crate.

    How many forces should there be in this diagram?Remember that a free-body diagram should contain actual forces, not components of forces.

    Answer:

    There is/are force(s) in the free-body diagram for the 7,2 kg crate.

    one-of
    type(string)
  2. Here is the diagram again:

    Which one of the following expressions is equal to the magnitude of the net force experienced by the 7,2 kg crate?

    TIP: Note that the angle is given to the horizontal!
    Answer:
  3. Here is the diagram again:

    Calculate the tension (T) in the cable connecting the two crates as well as the angle (α).

    INSTRUCTIONS:
    • Do not round any values from intermediate steps.
    • Round both of your final answers to two decimal places.
    • Use the values given here for any physical constants that you may need.
    Answer:

    T=

    α = °

    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))


ID is: 4622 Seed is: 7144

Swapping two blocks on a rough slope

Adapted from DBE Nov 2015 Grade 11, P1, Q4.1
Physical constants · Physics formulas

Two heavy wooden blocks of mass 12 kg and 24 kg respectively are placed on a rough slope inclined at an angle of 15° to the horizontal. The blocks are connected to each other by a light inextensible string. The sides of the blocks which touch the inclined slope have the same area.

A man pulls on the top block with a force of 210 N, via the string, and the system of blocks accelerates up the slope. The 12 kg block experiences a kinetic frictional force of 29 N and the 24 kg block experiences a kinetic frictional force of 58 N.

The blocks are now swapped with each other so that the same 210 N force is now acting on the 12 kg block as shown in the diagram below.

  1. How will the magnitude of the acceleration of the system change?
  2. How will the tension in the string connecting the two blocks change?
Answer:
  • a will
  • T will

ID is: 4622 Seed is: 9553

Swapping two blocks on a rough slope

Adapted from DBE Nov 2015 Grade 11, P1, Q4.1
Physical constants · Physics formulas

Two heavy wooden blocks of mass 15 kg and 30 kg respectively are placed on a rough slope inclined at an angle of 10° to the horizontal. The blocks are connected to each other by a light inextensible cable. The sides of the blocks which touch the inclined slope have the same area.

A boy pulls on the top block with a force of 190 N, via the cable, and the system of blocks accelerates up the slope. The 15 kg block experiences a kinetic frictional force of 30 N and the 30 kg block experiences a kinetic frictional force of 60 N.

The blocks are now swapped with each other so that the same 190 N force is now acting on the 15 kg block as shown in the diagram below.

  1. How will the magnitude of the acceleration of the system change?
  2. How will the tension in the cable connecting the two blocks change?
Answer:
  • a will
  • T will


ID is: 3449 Seed is: 1834

Pulley and a rough horizontal surface

A block of mass m1 is attached to a block of mass m2= 6,8 kg via a light inextensible string which is passed over a frictionless pulley as shown in the diagram below. The block of mass 6,8 kg is at rest on a horizontal surface and the block of mass m1 hangs vertically over the pulley. The coefficient of static friction between the block and the surface is μs and tension in the string is 130 N. The hanging mass is at its largest possible value for the system to only just remain in static equilibrium.

  1. Which one of the following is a correctly labelled free-body diagram indicating all the forces acting on the hanging block?

    A

    B

    C

    D

    Answer:

    The correct diagram is:

  2. Determine the mass of the hanging block as well as the coefficient of static friction between the block and the rough surface.

    INSTRUCTIONS:
    • Round both of your final answers to two decimal places.
    • You must use these values for any physical constants that you might need.
    Answer:

    m1=

    μs=

    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))
  3. Describe what will happen to the hanging block if mass m2 (the block on the horizontal surface) is increased.

    Describe what will happen to the hanging block if mass m2 is decreased.

    Answer:

    If m2 is increased, the hanging block will .

    If m2 is decreased, the hanging block will .


ID is: 3449 Seed is: 5491

Pulley and a rough horizontal surface

A block of mass m1 is attached to a block of mass m2 via a massless inextensible string which is passed over a frictionless pulley as shown in the diagram below. The block of mass m2 is at rest on a horizontal surface and the block of mass m1 hangs vertically over the pulley. The coefficient of static friction between the block and the surface is 0,47 and tension in the string is 60 N. The hanging mass is at its largest possible value for the system to only just remain in static equilibrium.

  1. Which one of the following is a correctly labelled force diagram showing all the forces acting on the block on the horizontal surface?

    A

    B

    C

    D

    Answer:

    The correct diagram is:

  2. Determine the mass of the hanging block as well as the mass of the block on the horizontal surface.

    INSTRUCTIONS:
    • Round both of your final answers to two decimal places.
    • You must use these values for any physical constants that you might need.
    Answer:

    m1=

    m2=

    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))
  3. Describe what will happen to the hanging block if mass m2 (the block on the horizontal surface) is decreased.

    Describe what will happen to the hanging block if mass m2 is increased.

    Answer:

    If m2 is decreased, the hanging block will .

    If m2 is increased, the hanging block will .



ID is: 3669 Seed is: 9138

Systems on rough inclined planes

A box of mass 3 kg is connected to another box of mass 8 kg by a light inextensible cable. The system is pulled up a rough plane inclined at 43° to the horizontal, by means of a constant 130 N force parallel to the plane as shown in the diagram below.

The boxes are not made from the same material. The magnitude of the kinetic frictional force between the surface and the 8 kg box is 32,11 N. The coefficient of kinetic friction between the 3 kg box and the surface is 0,56.

  1. Calculate the magnitude of the kinetic frictional force between the 3 kg box and the surface of the plane.

    INSTRUCTION:
    • Round your answer to two decimal places.
    • Use the values given here for any physical constants that you may need.
    Answer:

    fk,1=

    one-of
    type(numeric.abserror(0.01))
  2. Calculate the magnitude of the tension in the cable connecting the two boxes.

    INSTRUCTION:
    • Round your answer to two decimal places.
    • Use the values given here for any physical constants that you may need.
    Answer:

    T=

    one-of
    type(numeric.abserror(0.01))

ID is: 3669 Seed is: 1665

Systems on rough inclined slopes

A block of mass 9 kg is connected to another block of mass 6 kg by a light inextensible string. The system is pulled up a rough slope inclined at 46° to the horizontal, by means of a constant 140 N force parallel to the slope as shown in the diagram below.

The blocks are not made from the same material. The magnitude of the kinetic frictional force between the surface and the 6 kg block is 15,93 N. The coefficient of kinetic friction between the 9 kg block and the surface is 0,39.

  1. Calculate the magnitude of the kinetic frictional force between the 9 kg block and the surface of the slope.

    INSTRUCTION:
    • Round your answer to two decimal places.
    • Use the values given here for any physical constants that you may need.
    Answer:

    fk,1=

    one-of
    type(numeric.abserror(0.01))
  2. Calculate the magnitude of the tension in the string connecting the two blocks.

    INSTRUCTION:
    • Round your answer to two decimal places.
    • Use the values given here for any physical constants that you may need.
    Answer:

    T=

    one-of
    type(numeric.abserror(0.01))


ID is: 4612 Seed is: 5676

Free-body diagrams with a pulley and an inclined plane

Adapted from DBE Nov 2016 Grade 11, P1, Q4
Physical constants · Physics formulas

Two containers of mass 12 kg and 6 kg respectively are joined with an inelastic string of negligible mass. The string runs over a massless and frictionless pulley. The 12 kg container is on a horizontal surface while the 6 kg container is on a ramp inclined at 40° to the horizontal. The coefficient of kinetic friction between both containers and the surface is 0,22. The 6 kg container accelerates down the slope.

Draw a free-body diagram showing all forces acting on the 12 kg container (the container on the horizontal surface). Then use your free-body diagram to answer the following questions about the 12 kg container.

  1. How many forces are parallel to the horizontal surface, or have a component parallel to the horizontal surface?
  2. In which direction does the tensional force act?
  3. In which direction does the frictional force act?
Answer:

For the 12 kg container:

  1. There is/are force(s) parallel to the horizontal surface, or that have a parallel component.
  2. The tensional force acts .
  3. The frictional force acts .
one-of
type(string.nocase)

ID is: 4612 Seed is: 2427

Free-body diagrams with a pulley and an inclined plane

Adapted from DBE Nov 2016 Grade 11, P1, Q4
Physical constants · Physics formulas

Two blocks of mass 6 kg and 12 kg respectively are joined with an inelastic string of negligible mass. The string runs over a massless and frictionless pulley. The 6 kg block is on a horizontal surface while the 12 kg block is on a ramp inclined at 50° to the horizontal. The coefficient of kinetic friction between both blocks and the surface is 0,14. The 12 kg block accelerates down the slope.

Draw a free-body diagram showing all forces acting on the 12 kg block (the block on the slope). Then use your free-body diagram to answer the following questions about the 12 kg block.

  1. How many forces are parallel to the surface of the slope, or have a component parallel to the surface of the slope?
  2. In which direction does the tensional force act?
  3. In which direction does the frictional force act?
Answer:

For the 12 kg block:

  1. There is/are force(s) parallel to the surface of the slope, or that have a parallel component.
  2. The tensional force acts .
  3. The frictional force acts .
one-of
type(string.nocase)


ID is: 3835 Seed is: 3363

Multiple choice: Feel the tension!

Adapted from DBE Feb-Mar 2017 Grade 12, P1, Q1.2
Physical constants · Physics formulas

The diagram below shows two blocks, A and B, suspended from a ceiling. The blocks are stationary and have the same mass, but different heights above the ground.

The connecting strings are massless and inextensible. The tensions in the strings attached to blocks A and B are TA and TB respectively. In the diagram below, the size of the box represents its mass.

Which one of the following statements about how the tensions compare to each other is correct?

A TA>TB
B TA<TB
C TA=TB
D impossible to determine
Answer:

ID is: 3835 Seed is: 5479

Multiple choice: Feel the tension!

Adapted from DBE Feb-Mar 2017 Grade 12, P1, Q1.2
Physical constants · Physics formulas

The diagram below shows two blocks, K and L, suspended from a ceiling. The blocks are stationary and have different masses and different heights above the ground.

The connecting strings are massless and inextensible. The tensions in the strings attached to blocks K and L are TK and TL respectively. In the diagram below, the size of the box represents its mass.

Which one of the following statements about how the tensions compare to each other is correct?

A TK>TL
B TK<TL
C TK=TL
D impossible to determine
Answer:


ID is: 3548 Seed is: 9681

Pulley and a frictionless horizontal surface

Two blocks of different mass are attached to each other via a light inextensible string which is placed over a massless and frictionless pulley. Block 1 (mass 6 kg) is placed on a smooth surface and attached to the wall by a second string which makes an angle of 46° to the vertical as shown in the diagram below. Block 2 (mass 5 kg) is left to hang freely. The entire system is in static equilibrium and all forms of friction can be ignored.

  1. Which one of the following is a correctly labelled force diagram showing all the forces acting on Block 1? The diagrams are all to scale.

    TIP: First draw the force diagram for Block 1 and then compare it to the options below.
    A
    B
    C
    D
    Answer:

    The correct diagram is:

  2. Determine the magnitude of the normal force exerted on Block 1.

    INSTRUCTIONS:
    • Round your final answer to two decimal places.
    • You must use these values for any physical constants that you might need.
    Answer:

    FN,1=

    one-of
    type(numeric.abserror(0.01))

ID is: 3548 Seed is: 1609

Pulley and a frictionless horizontal surface

Two blocks of different mass are attached to each other via a light inextensible string which is placed over a massless and frictionless pulley. Block 1 (mass 3 kg) is placed on a smooth surface and attached to the wall by a second string which makes an angle of 42° to the horizontal as shown in the diagram below. Block 2 (mass 2 kg) is left to hang freely. The entire system is in static equilibrium and all forms of friction can be ignored.

  1. Which one of the following is a correctly labelled force diagram showing all the forces acting on Block 1? The diagrams are all to scale.

    TIP: First draw the force diagram for Block 1 and then compare it to the options below.
    A
    B
    C
    D
    Answer:

    The correct diagram is:

  2. Determine the magnitude of the normal force exerted on Block 1.

    INSTRUCTIONS:
    • Round your final answer to two decimal places.
    • You must use these values for any physical constants that you might need.
    Answer:

    FN,1=

    one-of
    type(numeric.abserror(0.01))


ID is: 4017 Seed is: 8161

Maximum static friction on a rough slope

Adapted from WCED Metro Central Sep 2017 Grade 12, P1, Q2.2
Physical constants · Physics formulas

A heavy wooden crate is placed on a rough slope inclined at an angle to the horizontal. A light inextensible cable is connected to the crate and the cable is run over a massless and frictionless pulley situated at the top of the slope and connected to a motor. The motor pulls on the crate with a force F, via the cable. Refer to the diagram below (not to scale).

The value of the maximum static frictional force between the crate and slope is 32 N. The magnitude of the parallel component of the gravitational force acting on the crate is 45 N.

  1. Define the term maximum static frictional force in words.

    Answer:

    The maximum static frictional force (fs max) is the force that the relative motion between a object and a surface.

  2. For what range of values of the magnitude of the force applied by the motor (F) will the crate experience acceleration down the slope?

    Answer:

ID is: 4017 Seed is: 2685

Maximum static friction on a rough slope

Adapted from WCED Metro Central Sep 2017 Grade 12, P1, Q2.2
Physical constants · Physics formulas

A heavy wooden crate is placed on a rough slope inclined at an angle to the horizontal. A light inextensible cable is connected to the crate and the cable is run over a massless and frictionless pulley situated at the top of the slope and connected to a motor. The motor pulls on the crate with a force F, via the cable. Refer to the diagram below (not to scale).

The value of the maximum static frictional force between the crate and slope is 30 N. The magnitude of the parallel component of the gravitational force acting on the crate is 36 N.

  1. Define the term maximum static frictional force in words.

    Answer:

    The maximum static frictional force (fs max) is the force that the relative motion between a object and a surface.

  2. For what range of values of the magnitude of the force applied by the motor (F) will the crate experience acceleration up the slope?

    Answer:


ID is: 1554 Seed is: 2403

A system accelerating horizontally on a rough surface

Two crates, with masses 15 kg and 10 kg respectively, are connected with a thick rope as shown in the diagram below. A force of 500 N is applied towards the right on the 10 kg crate. The crates experience an acceleration of 3 m·s2 to the right.

The crates are made of the same material and so they experience the same coefficient of kinetic friction with the surface.

TIP: The frictional force experienced by each crate will be proportional to its mass. This is because the crates have the same coefficient of kinetic friction (μk).
  1. Calculate the magnitude and direction of the frictional force acting on the 10 kg crate (the crate on the right).

    INSTRUCTION: Round your answer to two decimal places.
    Answer:

    fk,2= N

    one-of
    type(numeric.abserror(0.01))
  2. Calculate the magnitude of the tension T in the rope.

    INSTRUCTION: Round your answer to two decimal places.
    Answer:

    T= N

    one-of
    type(numeric.abserror(0.01))

ID is: 1554 Seed is: 2174

A system accelerating horizontally on a rough surface

Two crates, with masses 10 kg and 35 kg respectively, are connected with a thick rope as shown in the diagram below. A force of 800 N is applied towards the right on the 35 kg crate. The crates experience an acceleration of 5 m·s2 to the right.

The crates are made of the same material and so they experience the same coefficient of kinetic friction with the surface.

TIP: The frictional force experienced by each crate will be proportional to its mass. This is because the crates have the same coefficient of kinetic friction (μk).
  1. Calculate the magnitude and direction of the frictional force acting on the 35 kg crate (the crate on the right).

    INSTRUCTION: Round your answer to two decimal places.
    Answer:

    fk,2= N

    one-of
    type(numeric.abserror(0.01))
  2. Calculate the magnitude of the tension T in the rope.

    INSTRUCTION: Round your answer to two decimal places.
    Answer:

    T= N

    one-of
    type(numeric.abserror(0.01))


ID is: 4611 Seed is: 2562

A pulley and a rough inclined plane

Adapted from DBE Nov 2016 Grade 11, P1, Q4
Physical constants · Physics formulas

Crate A and Crate B are joined with an inelastic string of negligible mass. The string runs over a massless and frictionless pulley. Crate A has a mass of 10 kg and is on a horizontal surface. Crate B has a mass of 20 kg and is on a ramp inclined at 34° to the horizontal. The coefficient of kinetic friction between both crates and the surface is 0,13. Crate B accelerates down the slope.

  1. Calculate the frictional force that the surface exerts on Crate B.

    INSTRUCTION: Round your answer to two decimal places.
    Answer:

    fk=

    one-of
    type(numeric.abserror(0.01))
  2. Calculate the magnitude of the acceleration of the system of crates.

    INSTRUCTION: Round your answer to two decimal places.
    Answer:

    a=

    one-of
    type(numeric.abserror(0.02))
  3. How will the acceleration of the system change if a small part of Crate A is removed and added to Crate B?

    Choose from increase, decrease, and remain the same, and explain your answer.

    Answer:

    The acceleration will .

    This is because:

    • The total mass of the system .
    • The parallel component of the gravitational force experienced by Crate B than the frictional force experienced by Crate B.
    • The frictional force experienced by Crate A .

ID is: 4611 Seed is: 2674

A pulley and a rough inclined plane

Adapted from DBE Nov 2016 Grade 11, P1, Q4
Physical constants · Physics formulas

Block A and Block B are joined with an inelastic string of negligible mass. The string runs over a massless and frictionless pulley. Block A has a mass of 4 kg and is on a horizontal surface. Block B has a mass of 2 kg and is on a ramp inclined at 47° to the horizontal. The coefficient of kinetic friction between both blocks and the surface is 0,24. Block B accelerates down the slope.

  1. Calculate the frictional force that the surface exerts on Block B.

    INSTRUCTION: Round your answer to two decimal places.
    Answer:

    fk=

    one-of
    type(numeric.abserror(0.01))
  2. Calculate the magnitude of the acceleration of the system of blocks.

    INSTRUCTION: Round your answer to two decimal places.
    Answer:

    a=

    one-of
    type(numeric.abserror(0.02))
  3. How will the acceleration of the system change if a small part of Block A is removed and added to Block B?

    Choose from increase, decrease, and remain the same, and explain your answer.

    Answer:

    The acceleration will .

    This is because:

    • The total mass of the system .
    • The parallel component of the gravitational force experienced by Block B than the frictional force experienced by Block B.
    • The frictional force experienced by Block A .


ID is: 4016 Seed is: 9933

A pulley and a smooth slope

Adapted from WCED Metro Central Sep 2017 Grade 12, P1, Q2.1
Physical constants · Physics formulas

Two heavy wooden crates of mass 24 kg and 12 kg respectively are placed on a smooth slope inclined at an angle of 17° to the horizontal. The crates are connected to each other by a light inextensible cable. The same type of cable is connected to the top crate, and the cable is run over a massless and frictionless pulley at the top of the slope and connected to a motor. Refer to the diagram below (not to scale).

The motor pulls on the top crate with a force of 130 N, via the cable. The force exerted by the motor is such that the system of crates accelerates up the slope with acceleration a. Ignore all forms of friction between the crates and the slope.

  1. Draw a free-body diagram showing all forces acting on the 12 kg crate (the top crate). Then use your free-body diagram to answer the following questions about the 12 kg crate.

    1. How many forces are parallel to the slope, or have a component parallel to the slope?
    2. In which direction does the tensional force act?
    3. Does the motor exert a force on this crate?
    Answer:

    For the top crate:

    1. There is/are force(s) parallel to the slope, or that have a parallel component.
    2. The tensional force acts .
    3. The motor exert a force on this crate.
    one-of
    type(string.nocase)
  2. Calculate the:

    1. acceleration of the system of crates.
    2. magnitude of the tensional force in the cable between the crates.
    INSTRUCTION: Round your answers to two decimal places.
    Answer:
    1. a=
    2. T=
    one-of
    type(numeric.abserror(0.01))
    numeric

ID is: 4016 Seed is: 3592

A pulley and a smooth slope

Adapted from WCED Metro Central Sep 2017 Grade 12, P1, Q2.1
Physical constants · Physics formulas

Two heavy wooden crates of mass 12 kg and 24 kg respectively are placed on a smooth slope inclined at an angle of 23° to the horizontal. The crates are connected to each other by a light inextensible cable. The same type of cable is connected to the top crate, and the cable is run over a massless and frictionless pulley at the top of the slope and connected to a motor. Refer to the diagram below (not to scale).

The motor pulls on the top crate with a force of 170 N, via the cable. The force exerted by the motor is such that the system of crates accelerates up the slope with acceleration a. Ignore all forms of friction between the crates and the slope.

  1. Draw a free-body diagram showing all forces acting on the 12 kg crate (the bottom crate). Then use your free-body diagram to answer the following questions about the 12 kg crate.

    1. How many forces are parallel to the slope, or have a component parallel to the slope?
    2. In which direction does the tensional force act?
    3. Does the motor exert a force on this crate?
    Answer:

    For the bottom crate:

    1. There is/are force(s) parallel to the slope, or that have a parallel component.
    2. The tensional force acts .
    3. The motor exert a force on this crate.
    one-of
    type(string.nocase)
  2. Calculate the:

    1. acceleration of the system of crates.
    2. magnitude of the tensional force in the cable between the crates.
    INSTRUCTION: Round your answers to two decimal places.
    Answer:
    1. a=
    2. T=
    one-of
    type(numeric.abserror(0.01))
    numeric


ID is: 3679 Seed is: 391

Physics is going to the dogs!

A team of dogs pulls two dog sleds across a frozen pond. The sled at the front has an unknown mass m2 and the sled at the back has a mass of 120 kg. The ropes attached to the dogs form an angle of 9° with the horizontal and the dogs pull with a constant force of 140 N.

While the sleds are being pulled, the front sled experiences a normal force of 770 N and the tension in the horizontal rope connecting the two sleds is T. All forms of friction can be ignored.

NOTE:

A sled is used for transport. It either has a flat bottom or long, thin strips of metal or wood attached to the bottom. A dog sled is pulled by one or more dogs (often huskies) and is used to move over ice and through snow. There are many different types of dog sled, with some being used for transport and others being used for racing.

  1. Calculate the acceleration of the sleds as well as the tension in the rope connecting the two sleds.

    INSTRUCTION:
    • Round both of your final answers to two decimal places.
    • Where appropriate, use unrounded answers from previous calculations.
    • Use the values given here for any physical constants that you may need.
    Answer:

    a=

    T=

    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))
  2. The dogs now pull the sleds through some thick snow and friction can no longer be ignored. Assume that the dog sleds are made from the same material, that the dogs continue pulling with the same strength and that the rope connected to the dogs is at the same angle as before.

    Perform a suitable calculation to determine which sled will experience the greater frictional force. Give a reason for your answer.

    Answer:

    The sled will experience the greater frictional force because it experiences the force.


ID is: 3679 Seed is: 8582

Physics is going to the dogs!

A team of dogs pulls two dog sleds across a frozen pond. The sled at the front has an unknown mass m2 and the sled at the back has a mass of 100 kg. The ropes attached to the dogs form an angle of 19° with the horizontal and the dogs pull with a constant force of 190 N.

While the sleds are being pulled, the front sled experiences a normal force of 760 N and the tension in the horizontal rope connecting the two sleds is T. All forms of friction can be ignored.

NOTE:

A sled is used for transport. It either has a flat bottom or long, thin strips of metal or wood attached to the bottom. A dog sled is pulled by one or more dogs (often huskies) and is used to move over ice and through snow. There are many different types of dog sled, with some being used for transport and others being used for racing.

  1. Calculate the acceleration of the sleds as well as the tension in the rope connecting the two sleds.

    INSTRUCTION:
    • Round both of your final answers to two decimal places.
    • Where appropriate, use unrounded answers from previous calculations.
    • Use the values given here for any physical constants that you may need.
    Answer:

    a=

    T=

    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))
  2. The dogs now pull the sleds through some thick snow and friction can no longer be ignored. Assume that the dog sleds are made from the same material, that the dogs continue pulling with the same strength and that the rope connected to the dogs is at the same angle as before.

    Perform a suitable calculation to determine which sled will experience the greater frictional force. Give a reason for your answer.

    Answer:

    The sled will experience the greater frictional force because it experiences the force.



ID is: 4619 Seed is: 8618

Two masses hanging over a pulley

Adapted from DBE Nov 2015 Grade 11, P1, Q4.2
Physical constants · Physics formulas

In the diagram below, a 4 kg mass and a 3 kg mass are connected by an inextensible string of negligible mass. The string is passed over a light, frictionless pulley so that the masses hang down as shown. Initially the system is held stationary.

All forms of friction and air resistance can be ignored.

Draw a labelled free-body diagram showing all the forces acting on the 4 kg mass once the system is released. Then choose the best diagram and labels from the options below.

Answer:

The best diagram for the 4 kg mass is:

The correct labels for the diagram are:


ID is: 4619 Seed is: 4122

Two masses hanging over a pulley

Adapted from DBE Nov 2015 Grade 11, P1, Q4.2
Physical constants · Physics formulas

In the diagram below, a 1 kg mass and an 8 kg mass are connected by an inextensible string of negligible mass. The string is passed over a light, frictionless pulley so that the masses hang down as shown. Initially the system is held stationary.

All forms of friction and air resistance can be ignored.

Draw a labelled free-body diagram showing all the forces acting on the 8 kg mass once the system is released. Then choose the best diagram and labels from the options below.

Answer:

The best diagram for the 8 kg mass is:

The correct labels for the diagram are:



ID is: 3673 Seed is: 9754

Motoring up the plane

A crate of mass 6,5 kg is connected to another crate of mass 3,4 kg by a light inextensible rope. The same type of rope is attached to the 3,4 kg crate, run over a light frictionless pulley, and connected to a motor.

The motor pulls the system up a smooth plane inclined at an angle α to the vertical. The motor applies a constant force of 90 N which causes the system to accelerate at 1,4 m·s2. The force applied by the motor is parallel to the plane as shown in the diagram below. Ignore all forms of friction.

  1. Calculate the tension (T) in the rope connecting the two crates as well as the angle (α).

    INSTRUCTION:
    • Do not round any values from intermediate steps.
    • Round both of your final answers to two decimal places.
    • Use the values given here for any physical constants that you may need.
    Answer:

    T=

    α = °

    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))
  2. The rope connecting the top crate to the motor suddenly snaps (breaks).

    What effect will this have on:

    1. the tension in the rope connecting the two crates?
    2. direction of acceleration of the crates?
    3. the magnitude of the acceleration of the crates?
    Answer:
    1. The magnitude of the tension in the rope connecting the two crates will .
    2. The crates will accelerate the plane.
    3. The magnitude of the acceleration will .

ID is: 3673 Seed is: 5729

Motoring up the ramp

A crate of mass 6,4 kg is connected to another crate of mass 9,2 kg by a light inextensible string. The same type of string is attached to the 9,2 kg crate, run over a light frictionless pulley, and connected to a motor.

The motor pulls the system up a smooth ramp inclined at an angle α to the vertical. The motor applies a constant force of 110 N which causes the system to accelerate at 0,23 m·s2. The force applied by the motor is parallel to the ramp as shown in the diagram below. Ignore all forms of friction.

  1. Calculate the tension (T) in the string connecting the two crates as well as the angle (α).

    INSTRUCTION:
    • Do not round any values from intermediate steps.
    • Round both of your final answers to two decimal places.
    • Use the values given here for any physical constants that you may need.
    Answer:

    T=

    α = °

    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))
  2. The string connecting the top crate to the motor suddenly snaps (breaks).

    What effect will this have on:

    1. the tension in the string connecting the two crates?
    2. direction of acceleration of the crates?
    3. the magnitude of the acceleration of the crates?
    Answer:
    1. The magnitude of the tension in the string connecting the two crates will .
    2. The crates will accelerate the ramp.
    3. The magnitude of the acceleration will .


ID is: 3614 Seed is: 5508

Hanging blocks

A block of mass 9,2 kg is connected to another block of mass 6,6 kg by a light inextensible cable. This system of blocks is then suspended from the ceiling by the top block, using the same type of cable.

  1. The hanging system of blocks is in static equilibrium. What does this mean?

    A The system is stationary because it experiences the static frictional force.
    B The forces acting on the system are balanced and the system does not move.
    C The system gently swings from side to side.
    D The system only experiences electrostatic forces.
    Answer:

    The correct statement is:

  2. Draw labelled free-body diagrams indicating all the forces acting on each block.

    Now compare your diagrams to the two diagrams given below and answer the questions that follow.

    Diagram A

    Diagram B

    1. Which diagram is the free-body diagram for the top block?
    2. Which force does Force P represent?
    Answer:
    1. Diagram is the free-body diagram for the top block.
    2. Force P represents the force acting on the block.
  3. Calculate the magnitude of the tensional force in the bottom cable (T2).

    INSTRUCTIONS:
    • Round your answer to one decimal place.
    • Use the values given here for any physical constants that you may need.
    Answer:

    T2=

    one-of
    type(numeric.abserror(0.1))
  4. Calculate the magnitude of the tensional force in the top cable (T1).

    INSTRUCTIONS:
    • Where appropriate, use unrounded answers from the previous question.
    • Round your answer to the nearest integer.
    • Use the values given here for any physical constants that you may need.
    Answer:

    T1=

    numeric

ID is: 3614 Seed is: 4202

Hanging blocks

A block of mass 5,3 kg is connected to another block of mass 9,7 kg by a light inextensible rope. This system of blocks is then suspended from the ceiling by the top block, using the same type of rope.

  1. The hanging system of blocks is in static equilibrium. What does this mean?

    A The system only experiences electrostatic forces.
    B The system gently swings from side to side.
    C The forces acting on the system are balanced and the system does not move.
    D The top block and the bottom block must have the same mass in order to be balanced.
    Answer:

    The correct statement is:

  2. Draw labelled free-body diagrams indicating all the forces acting on each block.

    Now compare your diagrams to the two diagrams given below and answer the questions that follow.

    Diagram A

    Diagram B

    1. Which diagram is the free-body diagram for the bottom block?
    2. Which force does Force P represent?
    Answer:
    1. Diagram is the free-body diagram for the bottom block.
    2. Force P represents the force acting on the block.
  3. Calculate the magnitude of the tensional force in the bottom rope (T2).

    INSTRUCTIONS:
    • Round your answer to one decimal place.
    • Use the values given here for any physical constants that you may need.
    Answer:

    T2=

    one-of
    type(numeric.abserror(0.1))
  4. Calculate the magnitude of the tensional force in the top rope (T1).

    INSTRUCTIONS:
    • Where appropriate, use unrounded answers from the previous question.
    • Round your answer to the nearest integer.
    • Use the values given here for any physical constants that you may need.
    Answer:

    T1=

    numeric

11. Newton's third law



ID is: 3795 Seed is: 5899

MCQ: Identifying action-reaction pairs

An ox is trying to pull a trailer with no wheels across a rough dirt path, but the trailer will not move.

The following diagram shows some of the forces involved in this scenario.

KEY:

  • F1: normal force of the trailer on the ground
  • F2: gravitational force of the trailer on the Earth
  • F3: gravitational force of the Earth on the trailer
  • F4: normal force of the ground on the trailer

Consider the following two pairs of forces:

(i) F1 and F2
(ii) F3 and F4

Which of the above pairs of forces are Newton's third law action-reaction pairs?

A (i) only
B (ii) only
C Both (i) and (ii)
D Neither (i) nor (ii)
Answer:

The correct option is: .


ID is: 3795 Seed is: 2258

MCQ: Identifying action-reaction pairs

A magnet is stuck to a fridge.

The following diagram shows some of the forces involved in this scenario.

KEY:

  • F1: normal force of the magnet on the fridge
  • F2: magnetic force of the magnet on the fridge
  • F3: magnetic force of the fridge on the magnet
  • F4: normal force of the fridge on the magnet

Consider the following two pairs of forces:

(i) F3 and F4
(ii) F1 and F4

Which of the above pairs of forces are Newton's third law action-reaction pairs?

A (i) only
B (ii) only
C Both (i) and (ii)
D Neither (i) nor (ii)
Answer:

The correct option is: .



ID is: 3643 Seed is: 1242

Statement: Newton's third law

Use the drop-down menus below to state Newton's third law of motion in words.

Answer:

When Object A Object B, Object B exerts of magnitude on Object A.


ID is: 3643 Seed is: 8469

Statement: Newton's third law

Use the drop-down menus below to state Newton's third law of motion in words.

Answer:

When Body A Body B, Body B exerts of magnitude on Body A.



ID is: 3322 Seed is: 3771

Properties of action-reaction pairs

Newton's third law talks about action-reaction pairs. Four statements about action-reaction pairs are given to you below. For each of these statements, indicate if they are true or false.

1 Action-reaction pairs have the same magnitude.
2 Action-reaction pairs occur at different times; the reaction follows the action.
3 Action-reaction pairs of forces can be different types of force.
4 Action-reaction pairs act on different objects.
Answer:

Statement 1 is .

Statement 2 is .

Statement 3 is .

Statement 4 is .


ID is: 3322 Seed is: 3338

Properties of action-reaction pairs

Newton's third law talks about action-reaction pairs. Four statements about action-reaction pairs are given to you below. For each of these statements, indicate if they are true or false.

1 Action-reaction pairs act in the same direction.
2 Action-reaction pairs arise as an interaction between two forces.
3 Action-reaction pairs occur at different times; the reaction follows the action.
4 All forces occur in action-reaction pairs.
Answer:

Statement 1 is .

Statement 2 is .

Statement 3 is .

Statement 4 is .



ID is: 3287 Seed is: 4270

Multiple choice: Newton's laws

A body with mass 2m exerts a force of magnitude F on a second body with mass m. This is a net force which causes the second body to have an acceleration of magnitude a.

Which one of the following statements is true regarding the force that the second object exerts on the first object and the acceleration experienced by the first object?

A The force has magnitude 12F and the acceleration has magnitude a.
B The force has magnitude F and the acceleration has magnitude a.
C The force has magnitude F and the acceleration has magnitude 12a.
D The force has magnitude 12F and the acceleration has magnitude 12a.
Answer: The correct option is: .

ID is: 3287 Seed is: 2759

Multiple choice: Newton's laws

An object with mass 3m exerts a force of magnitude F on a second object with mass m. This is a net force which causes the second object to have an acceleration of magnitude a.

Which one of the following statements is true regarding the force that the second object exerts on the first object and the acceleration experienced by the first object?

A The force has magnitude 13F and the acceleration has magnitude 13a.
B The force has magnitude 13F and the acceleration has magnitude a.
C The force has magnitude F and the acceleration has magnitude a.
D The force has magnitude F and the acceleration has magnitude 13a.
Answer: The correct option is: .


ID is: 3790 Seed is: 2664

Identifying action-reaction pairs

A box is at rest on a table.

One of the forces experienced by the box is the gravitational force (Fg). Describe the force that forms an action-reaction pair with Fg. Specify its direction, which object experiences the force, and which object exerts the force.

Answer:

Fg forms an action-reaction pair with the force exerted on the by the .


ID is: 3790 Seed is: 2493

Identifying action-reaction pairs

A book is at rest on a table.

One of the forces experienced by the book is the normal force (FN). Describe the force that forms an action-reaction pair with FN. Specify its direction, which object experiences the force, and which object exerts the force.

Answer:

FN forms an action-reaction pair with the force exerted on the by the .



ID is: 3793 Seed is: 8784

Action-reaction pairs

A cable is used to hang a ball vertically from the ceiling.

John and Ifedolapo draw a diagram and show some of the forces involved in this scenario.

KEY:

  • F1: tensional force of the cable on the ball
  • F2: tensional force of the ball on the cable
  • F3: gravitational force of the ball on the Earth
  • F4: gravitational force of the Earth on the ball
  1. John says that F3 and F4 can cancel each other out. This is John's explanation of why he thinks that F3 and F4 can cancel each other out:

    F3 and F4 form an action-reaction pair of forces. Forces in action-reaction pairs are always equal in magnitude and opposite in direction. So they will cancel each other out because their vector sum is zero. Which means that the net vertical force experienced by the ball will be zero.

    Wow! That sounds pretty convincing, but Ifedolapo disagrees and says that F3 and F4 cannot cancel each other out.

    Determine whether John is correct or incorrect and give a reason from the table below.

    F3 and F4 ...

    A are not opposite in direction
    B are not equal in magnitude
    C do not both act on the ball
    D are not an action-reaction pair
    Answer:

    John is because F3 and F4 .

  2. Which pair of forces does cancel out to keep the ball in equilibrium?

    Answer:

    and will cancel each other out.


ID is: 3793 Seed is: 173

Action-reaction pairs

A ball is falling down through the air at a constant velocity. As it falls it experiences air resistance.

Ifetayo and Oladapo draw a diagram and show some of the forces involved in this scenario.

KEY:

  • F1: air resistance of the air molecules on the ball
  • F2: gravitational force of the Earth on the ball
  • F3: air resistance of the ball on the air molecules
  • F4: gravitational force of the ball on the Earth
  1. Ifetayo says that F1 and F3 can cancel each other out. This is Ifetayo's explanation of why she thinks that F1 and F3 can cancel each other out:

    F1 and F3 form an action-reaction pair of forces. Forces in action-reaction pairs are always equal in magnitude and opposite in direction. So they will cancel each other out because their vector sum is zero. Which means that the net vertical force experienced by the ball will be zero.

    Wow! That sounds pretty convincing, but Oladapo disagrees and says that F1 and F3 cannot cancel each other out.

    Determine whether Ifetayo is correct or incorrect and give a reason from the table below.

    F1 and F3 ...

    A are not an action-reaction pair
    B act on different objects
    C are not opposite in direction
    D are not equal in magnitude
    Answer:

    Ifetayo is because F1 and F3 .

  2. Which pair of forces does cancel out to keep the ball in equilibrium?

    Answer:

    and will cancel each other out.



ID is: 1560 Seed is: 8864

Newton's third law

A butterfly hits the front windscreen of a moving train. How does the magnitude of the force the butterfly exerts on the windscreen compare to the magnitude of the force the windscreen exerts on the butterfly?

Answer: The magnitude of the force the butterfly exerts on the windscreen is .

ID is: 1560 Seed is: 2420

Newton's third law

A locust hits the front windscreen of a moving bus. How does the magnitude of the force the locust exerts on the windscreen compare to the magnitude of the force the windscreen exerts on the locust?

Answer: The magnitude of the force the locust exerts on the windscreen is .

12. Forces between masses

13. Newton's universal law of gravitation



ID is: 3861 Seed is: 9947

Planetary orbits

Rethabile is an astronomer and she is studying a planet which is orbiting a star in the Milky Way galaxy. The planet is a massive gas giant and has a mass of 5,18×1028 kg and its parent star has a mass of 4,61×1030 kg. Rethabile plots the position of the planet and its star on a Cartesian plane. The origin of the Cartesian plane is located at the centre of the star. Rethabile uses this graph to establish that the planet traces out an elliptical orbit around the sun.

On a particular date, Rethabile observes the planet at the coordinate (189;54,3) million km relative to the sun.

Calculate the gravitational force that the planet exerts on the star.

INSTRUCTIONS:
  • Give the magnitude of the force to two decimal places, in scientific notation.
  • Give the direction of the force, to one decimal place, as an angle measured anti-clockwise from the positive x-axis.
  • Use these values for any physical constants you might need.
Answer:

Fg= at ° anti-clockwise from the positive x-axis.

TIP: Do not give the angle as a bearing! You need to work with the angle the same way you would in maths.
numeric
one-of
type(numeric.abserror(0.1))

ID is: 3861 Seed is: 8599

Planetary orbits

Erioluwa is an astronomer and she is studying a planet which is orbiting a star in the Milky Way galaxy. The planet is a massive gas giant and has a mass of 7,69×1027 kg and its parent star has a mass of 1,75×1031 kg. Erioluwa plots the position of the planet and its star on a Cartesian plane. The origin of the Cartesian plane is located at the centre of the star. Erioluwa uses this graph to establish that the planet traces out an elliptical orbit around the sun.

On a particular date, Erioluwa observes the planet at the coordinate (467;556) million km relative to the sun.

Calculate the gravitational force that the planet exerts on the star.

INSTRUCTIONS:
  • Give the magnitude of the force to two decimal places, in scientific notation.
  • Give the direction of the force, to one decimal place, as an angle measured anti-clockwise from the positive x-axis.
  • Use these values for any physical constants you might need.
Answer:

Fg= at ° anti-clockwise from the positive x-axis.

TIP: Do not give the angle as a bearing! You need to work with the angle the same way you would in maths.
numeric
one-of
type(numeric.abserror(0.1))


ID is: 1542 Seed is: 6943

Newton's universal law of gravity

Two objects with masses of 9,2×1017 kg and 6,6×1017 kg respectively are 60 600 m apart. What is the gravitational force between the two objects?

INSTRUCTION:
  • Write your answer in scientific notation and then round it to two decimal places.
  • Use any physical constants you may need as listed here.
Answer:

Fg= N

numeric

ID is: 1542 Seed is: 8968

Newton's universal law of gravity

Two objects with masses of 9,5×1017 kg and 9,8×1017 kg exert a gravitational force on each other of 1,84×1016 N. What is the distance between the centres of the two objects?

INSTRUCTION:
  • Write your answer in scientific notation and then round it to two decimal places.
  • Use any physical constants you may need as listed here.
Answer:

d= m

numeric


ID is: 4604 Seed is: 2125

Gravitational forces with satellites

Adapted from DBE Nov 2016 Grade 11, P1, Q5
Physical constants · Physics formulas

Two satellites are orbiting the planet Neptune. Satellite A has a mass of 4 000 kg. Satellite A is at a height of 128 000 km above the surface of Neptune and Satellite B is at a height of 150 000 km above the surface of Neptune.

Neptune has a mass of 1,02×1026 kg and a radius of 2,48×107 m.

  1. Calculate the magnitude of the gravitational force between Neptune and Satellite A.

    INSTRUCTION: Round your answer to two decimal places.
    Answer:

    Fg=

    one-of
    type(numeric.abserror(0.01))
  2. What mass would Satellite B need to have in order to experience a force with the same magnitude as the force experienced by Satellite A?

    Choose from greater than, less than, or equal to the mass of Satellite A. Give a reason for your answer.

    Answer:

    The mass of Satellite B would need to be the mass of Satellite A.

    This is because:

    • The height of Satellite B is the height of Satellite A
    • and the mass of Neptune is .
    • So for gravitational force,
    • the mass of Satellite B must be the mass of Satellite A.

ID is: 4604 Seed is: 7602

Gravitational forces with satellites

Adapted from DBE Nov 2016 Grade 11, P1, Q5
Physical constants · Physics formulas

Two space probes are orbiting the dwarf planet Pluto. Space Probe A has a mass of 4 000 kg and Space Probe B has a mass of 1 600 kg. Space Probe A is at a height of 6 100 km above the surface of Pluto.

Pluto has a mass of 1,31×1022 kg and a radius of 1,19×106 m.

  1. Calculate the magnitude of the gravitational force between Pluto and Space Probe A.

    INSTRUCTION: Round your answer to two decimal places.
    Answer:

    Fg=

    one-of
    type(numeric.abserror(0.01))
  2. What height above the surface of Pluto should Space Probe B be in order to experience a force with the same magnitude as the force experienced by Space Probe A?

    Choose from greater than, less than, or equal to the height of Space Probe A. Give a reason for your answer.

    Answer:

    The height of Space Probe B would need to be the height of Space Probe A.

    This is because:

    • The mass of Space Probe B is the mass of Space Probe A
    • and the mass of Pluto is .
    • So for gravitational force,
    • the height of Space Probe B must be the height of Space Probe A.


ID is: 3807 Seed is: 6374

Understanding Newton's universal law of gravitation

The following relationship is a useful equation in mechanics:

Fg=Gm1m2d2

It is the mathematical form of Newton's universal law of gravitation.

  1. What does the symbol m2 stand for?

    A bigger mass
    B smaller mass
    C mass of one object
    D metres
    Answer:

    The meaning of m2 is .

  2. What is the SI unit in which we measure Fg?

    Answer:

    The SI unit in which we measure Fg is .


ID is: 3807 Seed is: 5469

Understanding Newton's universal law of gravitation

The following relationship is an important equation in mechanics:

Fg=Gm1m2d2

It is the mathematical form of Newton's universal law of gravitation.

  1. What does the symbol d stand for?

    A diameter of a planet
    B density of mass
    C distance between the masses
    D distance from the sun
    Answer:

    The meaning of d is .

  2. What is the SI unit used to measure d?

    Answer:

    The SI unit used to measure d is .



ID is: 1561 Seed is: 134

Terminology: Newton's laws

Complete the definition/law or provide the term asked for:

TIP: You can't just make the statement true in a specific case. If it's a definition, then it needs to be generally true.
  1. Newton's _______ law of motion states: If a resultant force acts on a body, it will cause the body to accelerate in the direction of the resultant force. The acceleration of the body will be directly proportional to the resultant force and inversely proportional to the mass of the body.

    Answer:
    one-of
    type(string.nocase)
  2. Name the force that opposes the motion of a object in contact with a surface and it acts parallel to the surface the object is in contact with.

    Answer:
    one-of
    type(string.nocase)

ID is: 1561 Seed is: 4101

Terminology: Newton's laws

Complete the definition/law or provide the term asked for:

TIP: You can't just make the statement true in a specific case. If it's a definition, then it needs to be generally true.
  1. An object in _______ has the vector sum of all the forces acting on it equal to zero.

    Answer:
    one-of
    type(string.nocase)
  2. Newton's _______ law of motion states: If body A exerts a force on body B, then body B exerts a force of equal magnitude on body A, but in the opposite direction.

    Answer:
    one-of
    type(string.nocase)


ID is: 3827 Seed is: 8539

Losing weight on holiday

Mpho is on holiday in Paris (in France) which is at an altitude of 45 m above sea-level. He climbs the stairs to the top of the Eiffel Tower, which has a total height of 325 m above the ground. Mpho has a mass of 64 kg.

The mass of the Earth is 5,972×1024 kg. The distance from the centre of the Earth to sea-level is 6 371 km .

INSTRUCTIONS:
  • Round all numerical answers to five decimal places.
  • You cannot assume that g=9,8 m·s2 anywhere in this question!
  1. What is Mpho's weight at the bottom of the Eiffel Tower?

    Answer:

    Mpho's weight is at the bottom.

    one-of
    type(numeric.abserror(1e-05))
  2. Mpho has been studying physics during his holiday and knows that the gravitational force decreases in magnitude as distance increases. He wonders what fraction of his weight he will have lost during his climb up the Eiffel Tower.

    1. What percentage of his weight does Mpho lose when climbing to the top of the Eiffel Tower?
    2. Does Mpho lose mass when climbing to the top of the Eiffel Tower?
    Answer:
    1. Mpho loses % of his weight.
    2. Mpho lose any mass.
    one-of
    type(numeric.abserror(5e-05))

ID is: 3827 Seed is: 1181

Losing weight on holiday

Dumile is on holiday in Doha (in Qatar) which is at an altitude of 14 m above sea-level. He climbs the stairs to the top of the Aspire Tower, which has a total height of 300 m above the ground. Dumile has a mass of 62 kg.

The mass of the Earth is 5,972×1024 kg. The distance from the centre of the Earth to sea-level is 6 371 km .

INSTRUCTIONS:
  • Round all numerical answers to five decimal places.
  • You cannot assume that g=9,8 m·s2 anywhere in this question!
  1. What is Dumile's weight at the bottom of the Aspire Tower?

    Answer:

    Dumile's weight is at the bottom.

    one-of
    type(numeric.abserror(1e-05))
  2. Dumile has been studying physics during his holiday and knows that the gravitational force decreases in magnitude as distance increases. He wonders what fraction of his weight he will have lost during his climb up the Aspire Tower.

    1. What percentage of his weight does Dumile lose when climbing to the top of the Aspire Tower?
    2. Does Dumile lose mass when climbing to the top of the Aspire Tower?
    Answer:
    1. Dumile loses % of his weight.
    2. Dumile lose any mass.
    one-of
    type(numeric.abserror(5e-05))


ID is: 3859 Seed is: 7655

Gravitational forces in space

In a distant galaxy, two planets, X and Y, are interacting gravitationally. Planet X has a mass of 4,48×1028 kg and Planet Y has a mass of 2,45×1024 kg. When the distance between them is d, Planet Y exerts a gravitational force of 1,17×1027 N on Planet X.

  1. Determine the distance between the planets (d).

    INSTRUCTIONS:
    • Write your answer in scientific notation and then give it rounded to two decimal places.
    • Use these physical constants for any calculations.
    Answer:

    d=

    numeric
    1. What is the gravitational force exerted on Planet Y by Planet X?

      A The force points towards Y and away from X, and has a magnitude less than 1,17×1027 N.
      B The force points towards Y and away from X, and has a magnitude equal to 1,17×1027 N.
      C The force points towards X and away from Y, and has a magnitude equal to 1,17×1027 N.
      D The force points towards X and away from Y, and has a magnitude less than 1,17×1027 N.
    2. Which of Newton's laws of motion should you use to answer the above question?
    Answer:
    1. The gravitational force of X on Y is .
    2. The law to use is Newton's law of motion.

ID is: 3859 Seed is: 7654

Gravitational forces in space

In a distant galaxy, two asteroids, X and Y, are interacting gravitationally. Asteroid X has a mass mX and Asteroid Y has a mass of 7,50×1014 kg. When the distance between them is 4,61×108 m, Asteroid X exerts a gravitational force of 2,29×100 N on Asteroid Y.

  1. Determine the mass of Asteroid X (mX).

    INSTRUCTIONS:
    • Write your answer in scientific notation and then give it rounded to two decimal places.
    • Use these physical constants for any calculations.
    Answer:

    mX=

    numeric
    1. What is the gravitational force exerted on Asteroid X by Asteroid Y?

      A The force points towards Y and away from X, and has a magnitude equal to 2,29×100 N.
      B The force points towards Y and away from X, and has a magnitude less than 2,29×100 N.
      C The force points towards X and away from Y, and has a magnitude equal to 2,29×100 N.
      D The force points towards X and away from Y, and has a magnitude less than 2,29×100 N.
    2. Which of Newton's laws of motion should you use to answer the above question?
    Answer:
    1. The gravitational force of Y on X is .
    2. The law to use is Newton's law of motion.


ID is: 3826 Seed is: 7245

Space rocket

A space rocket of mass 21 200 kg is orbiting Ariel (a moon of Uranus) at a height of 1 780 km above the surface of Ariel. The rocket has switched off its engines and is effectively in free-fall as it orbits in a circular path.

Ariel has a mass of 1,35×1021 kg and a radius of 5,789×102 km.

  1. Calculate the force of gravity experienced by the rocket.

    INSTRUCTIONS:
    • Round your answer to three decimal places in scientific notation.
    • You must use these values for any physical constants you might need.
    Answer:

    Fg=

    numeric
  2. Calculate the acceleration of the rocket as it orbits Ariel.

    INSTRUCTIONS:
    • Round your answer to four decimal places.
    • Where necessary, use unrounded values from Question 1.
    Answer:

    a= .

    one-of
    type(numeric.abserror(0.0001))
  3. The rocket orbits Ariel with a constant speed. How is it possible for the rocket to have a non-zero acceleration and maintain a constant speed?

    A It's not possible. The acceleration of the rocket must be zero.
    B The acceleration changes the direction of motion, but not the speed of the rocket.
    C The rocket constantly needs to fire the engines to brake to maintain a constant speed.
    D It's not possible. The rocket's speed will increase.
    Answer:

    The correct option is:


ID is: 3826 Seed is: 9187

Space rocket

A space rocket of mass 22 700 kg is orbiting Europa (a moon of Jupiter) at a height of 1 060 km above the surface of Europa. The rocket has switched off its engines and is effectively in free-fall as it orbits in a circular path.

Europa has a mass of 4,80×1022 kg and a radius of 1,561×103 km.

  1. Calculate the force of gravity experienced by the rocket.

    INSTRUCTIONS:
    • Give your answer rounded to three decimal places in scientific notation.
    • You must use these values for any physical constants you might need.
    Answer:

    Fg=

    numeric
  2. Calculate the acceleration of the rocket as it orbits Europa.

    INSTRUCTIONS:
    • Round your answer to three decimal places.
    • Where necessary, use unrounded values from Question 1.
    Answer:

    a= .

    one-of
    type(numeric.abserror(0.001))
  3. The rocket orbits Europa with a constant speed. How is it possible for the rocket to have a non-zero acceleration and maintain a constant speed?

    A It's not possible. The rocket's speed will increase.
    B It's not possible. The acceleration of the rocket must be zero.
    C The acceleration changes the direction of motion, but not the speed of the rocket.
    D The rocket constantly needs to fire the engines to brake to maintain a constant speed.
    Answer:

    The correct option is:



ID is: 4626 Seed is: 4593

The gravitational force between the sun and different planets

Adapted from DBE Nov 2015 Grade 11, P1, Q5
Physical constants · Physics formulas

The dwarf planet Ceres has a mass of 9,39×1020 kg. As it orbits the sun, it experiences a gravitational force.

The mass of the sun is 2,12×109 times greater than that of Ceres. At a certain point in Ceres's orbit, the distance between the centres of the sun and Ceres is 4,24×1011 m.

  1. Calculate the magnitude of the gravitational force that the sun exerts on Ceres.

    INSTRUCTION: Write your answer in scientific notation and then round it to two decimal places.
    Answer:

    Fg=

    numeric
  2. How will the gravitational force that Ceres exerts on the sun compare to the gravitational force that the sun exerts on Ceres? Give a reason for your answer.

    Answer:

    The gravitational force that Ceres exerts on the sun will be the gravitational force that the sun exerts on Ceres.

    This is because:


ID is: 4626 Seed is: 102

The gravitational force between the sun and different planets

Adapted from DBE Nov 2015 Grade 11, P1, Q5
Physical constants · Physics formulas

The planet Jupiter has a mass of 1,90×1027 kg. As it orbits the sun, it experiences a gravitational force.

The mass of the sun is 1 050 times greater than that of Jupiter. At a certain point in Jupiter's orbit, the sun exerts a gravitational force with a magnitude of 4,00×1023 N on Jupiter.

  1. Calculate the distance between the sun and Jupiter.

    INSTRUCTION: Write your answer in scientific notation and then round it to two decimal places.
    Answer:

    d=

    numeric
  2. How will the gravitational force that Jupiter exerts on the sun compare to the gravitational force that the sun exerts on Jupiter? Give a reason for your answer.

    Answer:

    The gravitational force that Jupiter exerts on the sun will be the gravitational force that the sun exerts on Jupiter.

    This is because:



ID is: 3320 Seed is: 1864

Acceleration due to gravity on any planet

Karabou travels in a spaceship to Pluto (a dwarf planet). She needs to know what kind of conditions to prepare for. In particular, she needs to know the average acceleration due to gravity on the surface of Pluto in order to land safely. The mass of Pluto is 1,318×1022 kg and it has a radius of 1 187,2 km.

Calculate the magnitude of the acceleration due gravity near the surface of Pluto.

INSTRUCTIONS:
  • Round your answer to three decimal places.
  • You must use these values for any physical constants you might need.
Answer:

gPluto =

one-of
type(numeric.abserror(0.001))

ID is: 3320 Seed is: 6919

Acceleration due to gravity on any planet

Oluchi travels in a spaceship to Saturn (a planet). She needs to know what kind of conditions to prepare for. In particular, she needs to know the average acceleration due to gravity on the surface of Saturn in order to land safely. The mass of Saturn is 5,721×1026 kg and it has a radius of 60 153,3 km.

Calculate the magnitude of the acceleration due gravity near the surface of Saturn.

INSTRUCTIONS:
  • Round your answer to two decimal places.
  • You must use these values for any physical constants you might need.
Answer:

gSaturn =

one-of
type(numeric.abserror(0.01))


ID is: 3860 Seed is: 2307

Comets!

Amina is an astronomer and she is studying comets with different types of trajectory. One comet she is studying has an elliptical orbit around a star somewhere in the Milky Way.

NOTE: See how the tail of the comet points directly away from the star? The tail doesn't tell you anything about the direction of motion of the comet!
    1. Identify the type of force experienced by the comet at Point P.
    2. How does the force that the comet exerts on the star compare to the force that the star exerts on the comet at Point Q?
    Answer:
    1. At Point P, the comet experiences force.
    2. At Point Q, the magnitude of the force that the comet exerts on the star is the magnitude of the force that the star exerts on the comet. These forces are in .
  1. How does the acceleration experienced by the comet at Point S compare to the acceleration at Point R? Refer to the magnitudes as well as the directions of the accelerations as part of your answer.

    Answer:

    The magnitude of the acceleration at Point S is the magnitude of the acceleration at Point R.

    of the accelerations point . At Point S the acceleration points and at Point R the acceleration points .


ID is: 3860 Seed is: 1447

Comets!

Matlhodi is an astronomer and she is studying comets with different types of trajectory. One comet she is studying has an elliptical orbit around a star somewhere in the Milky Way.

NOTE: See how the tail of the comet points directly away from the star? The tail doesn't tell you anything about the direction of motion of the comet!
    1. Identify the type of force experienced by the comet at Point A.
    2. How does the force that the comet exerts on the star compare to the force that the star exerts on the comet at Point B?
    Answer:
    1. At Point A, the comet experiences force.
    2. At Point B, the magnitude of the force that the comet exerts on the star is the magnitude of the force that the star exerts on the comet. These forces are in .
  1. How does the acceleration experienced by the comet at Point C compare to the acceleration at Point D? Refer to the magnitudes as well as the directions of the accelerations as part of your answer.

    Answer:

    The magnitude of the acceleration at Point C is the magnitude of the acceleration at Point D.

    of the accelerations point . At Point C the acceleration points and at Point D the acceleration points .



ID is: 1466 Seed is: 4801

Gravitational force between planets

When the planet Venus is furthest from Earth it is 44 600 000 000,0 m away. The planet Venus has a mass of 4,87×1024 kg, and the Earth has a mass of 5,97×1024 kg.

What is the magnitude of the gravitational force between the planet Venus and the Earth?

INSTRUCTIONS:
  • Write your answer in scientific notation and then round it to two decimal places.
  • You must use these values for any physical constants that you might need.
Answer:

Fg= N

numeric

ID is: 1466 Seed is: 3132

Gravitational force between planets

When the planet Mars is closest to Earth it is 54 600 000 000,0 m away. The planet Mars has a mass of 6,42×1023 kg, and the Earth has a mass of 5,97×1024 kg.

What is the magnitude of the gravitational force between the planet Mars and the Earth?

INSTRUCTIONS:
  • Write your answer in scientific notation and then round it to two decimal places.
  • You must use these values for any physical constants that you might need.
Answer:

Fg= N

numeric


ID is: 3644 Seed is: 9749

Statement: Newton's universal law of gravitation

Adapted from DBE Nov 2015 & 2016 Grade 11, P1, Q5
Physical constants · Physics formulas

State Newton's universal law of gravitation in words.

Answer:

Each body in the universe every other body with a gravitational force that is the their masses and the of the distance between their centres.


ID is: 3644 Seed is: 40

Statement: Newton's universal law of gravitation

Adapted from DBE Nov 2015 & 2016 Grade 11, P1, Q5
Physical constants · Physics formulas

State Newton's universal law of gravitation in words.

Answer:

Each body in the universe every other body with a gravitational force that is the their masses and the of the distance between their centres.

14. Weight and mass



ID is: 3427 Seed is: 7296

Calculating weight on other planets

Adaeze is exploring Pluto (a dwarf planet). She is expecting a capsule of supplies with a mass of 1 740 kg to be delivered to Pluto so she can continue her mission. Pluto has a gravitational acceleration of 0,62 m·s2.

Calculate the weight of the capsule on Pluto.

INSTRUCTIONS:
  • Round your answer to two decimal places.
  • You must use these values for any physical constants you might need.
Answer:

Fg,Pluto=

one-of
type(numeric.abserror(0.01))

ID is: 3427 Seed is: 3631

Calculating weight on other planets

Danjuma is exploring Umbriel (a moon of Uranus). He is expecting a package of supplies with a mass of 2 720 kg to be delivered to Umbriel so he can continue his mission. Umbriel has a gravitational acceleration of 0,23 m·s2.

Calculate the gravitational force acting on the package on Umbriel.

INSTRUCTIONS:
  • Round your answer to two decimal places.
  • You must use these values for any physical constants you might need.
Answer:

Fg,Umbriel=

one-of
type(numeric.abserror(0.01))


ID is: 3637 Seed is: 8495

The relationship between Fg, g, and m

Gravitational force (Fg), gravitational acceleration (g), and mass (m) are three important quantities in mechanics.

Which one of the following equations correctly represents the relationship between these quantities?

A m=gFg
B m=Fgg
C m=gFg
Answer:

ID is: 3637 Seed is: 9853

The relationship between g, Fg, and m

Gravitational acceleration (g), gravitational force (Fg), and mass (m) are three important quantities in mechanics.

Which one of the following equations correctly represents the relationship between these quantities?

A m=gFg
B m=Fgg
C m=gFg
Answer:


ID is: 3646 Seed is: 4300

Definitions: weight and mass

Define weight and mass, using the drop-down menus below.

Answer:

Weight is the the Earth (or any planet-like body) exerts on any object on or near its surface. The SI unit for weight is the .

Mass is a measure of how much is inside an object. The SI unit for mass is the .


ID is: 3646 Seed is: 7299

Definitions: mass and weight

Define mass and weight, using the drop-down menus below.

Answer:

Mass is a measure of how much is inside an object. The SI unit for mass is the .

Weight is the the Earth (or any planet-like body) exerts on any object on or near its surface. The SI unit for weight is the .



ID is: 3813 Seed is: 3664

Mass and weight on Earth

A desk on the Earth's surface has a mass of 47 kg.

Calculate the weight of the desk.

INSTRUCTIONS:
  • Round your answer to one decimal place.
  • Choose the correct unit for weight from the drop-down menu.
  • Use any physical constants that you may need as listed here.
Answer: The weight of the desk is .
one-of
type(numeric.abserror(0.1))

ID is: 3813 Seed is: 7911

Mass and weight on Earth

A table on the Earth's surface has a mass of 99 kg.

Calculate the weight of the table.

INSTRUCTIONS:
  • Round your answer to one decimal place.
  • Choose the correct unit for weight from the drop-down menu.
  • Use any physical constants that you may need as listed here.
Answer: The weight of the table is .
one-of
type(numeric.abserror(0.1))


ID is: 3814 Seed is: 4819

Apparent weight, true weight, and weightlessness

An astronaut is in a rocket which is accelerating upwards, away from the surface of the Earth.

  1. How does the apparent weight of the astronaut compare to her true weight?
  2. Does the astronaut experience weightlessness?
Answer:
  1. The astronaut's apparent weight is her true weight.
  2. The astronaut experience weightlessness.

ID is: 3814 Seed is: 2777

Apparent weight, true weight, and weightlessness

A girl is sitting in a roller coaster which is accelerating downwards.

  1. How does the apparent weight of the girl compare to her true weight?
  2. Does the girl experience weightlessness?
Answer:
  1. The girl's apparent weight is her true weight.
  2. The girl experience weightlessness.


ID is: 3799 Seed is: 6317

Mass and weight

Mass and weight are related to each other, but they are different quantities in physics.

The lists below summarise some important differences between mass and weight. But each list is missing two pieces of information! Complete the lists by selecting the correct choices.

Answer:

Mass:

  • is an amount of matter
  • has the symbol
  • is measured in SI units of kg
  • depend on location

Weight:

  • is an amount of force
  • has the symbol
  • is measured in SI units of N
  • depend on location

ID is: 3799 Seed is: 6176

Mass and weight

Mass and weight are related to each other, but they are different quantities in physics.

The lists below summarise some important differences between mass and weight. But each list is missing two pieces of information! Complete the lists by selecting the correct choices.

Answer:

Mass:

  • is an amount of matter
  • has the symbol
  • is measured in SI units of kg
  • depend on location

Weight:

  • is an amount of force
  • has the symbol
  • is measured in SI units of N
  • depend on location


ID is: 3798 Seed is: 6995

Units of mass and weight

Use the dropdown menus to provide the missing units in the the scenario described below.

Answer: A large sack of maize has a mass of 35 and a weight of 343 .

ID is: 3798 Seed is: 5255

Units of mass and weight

Use the dropdown menus to provide the missing units in the the scenario described below.

Answer: A girl studying for her history test has a weight of 657 and a mass of 67 .


ID is: 3475 Seed is: 2754

Gravity on other planets

Joanna wants to know how the solar system evolved to its current state. While exploring the solar system, she decides to land on Iapetus (a moon of Saturn).

  1. In order to land the spacecraft safely on the surface of Iapetus, Joanna needs to gather some additional information. The mass of Iapetus is 1,993×1021 kg and it has a radius of 729,3 km.

    Calculate the magnitude of the acceleration due gravity near the surface of Iapetus.

    INSTRUCTION:
    • Round your answer to three decimal places.
    • Use the values for any physical constants you may need, as listed here.
    Answer:

    gIapetus=

    one-of
    type(numeric.abserror(0.001))
  2. After safely landing on Iapetus, Joanna analyses the composition of an interesting boulder. The boulder has a mass of 19 300 kg.

    Calculate the weight of the boulder.

    INSTRUCTION:
    • Where applicable, use unrounded values from Question 1.
    • Round your answer to the nearest 10 N.
    Answer:

    Fg=

    numeric

ID is: 3475 Seed is: 7321

Gravity on other planets

Heather wants to know how the solar system evolved to its current state. While exploring the solar system, she decides to land on Titania (a moon of Uranus).

  1. In order to land the spacecraft safely on the surface of Titania, Heather needs to gather some additional information. The mass of Titania is 3,51×1021 kg and it has a radius of 796,0 km.

    Calculate the magnitude of the acceleration due gravity near the surface of Titania.

    INSTRUCTION:
    • Round your answer to two decimal places.
    • Use the values for any physical constants you may need, as listed here.
    Answer:

    gTitania=

    one-of
    type(numeric.abserror(0.01))
  2. After safely landing on Titania, Heather analyses the composition of an interesting rock. The rock has a weight of 4 880 N.

    Calculate the mass of the rock.

    INSTRUCTION:
    • Where applicable, use unrounded values from Question 1.
    • Round your answer to the nearest 100 kg.
    Answer:

    m=

    numeric


ID is: 3656 Seed is: 6338

Understanding Fg=mg

The relationship Fg=mg is an important equation in mechanics.

  1. What does the symbol Fg represent?

    Answer:

    The symbol Fg represents .

  2. What is the SI unit in which we measure m?

    Answer:

    The SI unit in which we measure m is .


ID is: 3656 Seed is: 2275

Understanding Fg=mg

The relationship Fg=mg is a useful equation in mechanics.

  1. What does the symbol g represent?

    Answer:

    The symbol g represents .

  2. What is the SI unit used to measure m?

    Answer:

    The SI unit used to measure m is .



ID is: 3862 Seed is: 3111

Experiment: Weight on other planets

Chidi is an astronaut. He performs an experiment to see how his weight varies from place to place in the solar system. He takes his dad's bathroom scale and sets off in his spaceship to measure his weight near the surface of different planets, moons, and asteroids in the solar system.

He obtains the following results:

Location Weight (N)
Earth 767,3
Neptune (a planet) 872,3
Mars (a planet) 290,7
Eris (an asteroid and dwarf planet) 64,5
Titania (a moon of Uranus) 29,6
  1. Identify the independent, the dependent, and a fixed variable in Chidi's investigation:

    Answer:
    Independent
    Dependent
    Fixed
  2. Here is Chidi's data table again:

    Location Weight (N)
    Earth 767,3
    Neptune (a planet) 872,3
    Mars (a planet) 290,7
    Eris (an asteroid and dwarf planet) 64,5
    Titania (a moon of Uranus) 29,6

    Use this table to calculate:

    1. Chidi's mass (m).
    2. The local acceleration due to gravity on Mars (gMars).
    3. The mass of Mars (MMars) if its radius is 3,396×106 m.
    INSTRUCTIONS:
    • Round all answers to two decimal places.
    • The mass of Mars should be in scientific notation.
    • You must use these values for any physical constants required in your calculations.
    • You might find some of these physics formulas useful.
    Answer:
    1. m=
    2. gMars=
    3. MMars=
    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.scientific.abserror(1e+21))
  3. Chidi uses the data from the table to produce a graph. What type of graph should Chidi use? Give a reason for your answer.

    Answer: Chidi should use a because the data is and make up a whole.

ID is: 3862 Seed is: 3350

Experiment: Weight on other planets

Courtney is an astronaut. She performs an experiment to see how her weight varies from place to place in the solar system. She takes her mom's bathroom scale and sets off in her spaceship to measure her weight near the surface of different planets, moons, and asteroids in the solar system.

She obtains the following results:

Location Weight (N)
Earth 553,3
Rhea (a moon of Saturn) 15,0
Saturn (a planet) 589,4
Pluto (a dwarf planet) 35,1
Mars (a planet) 209,7
  1. Identify the independent, the dependent, and a fixed variable in Courtney's investigation:

    Answer:
    Independent
    Dependent
    Fixed
  2. Here is Courtney's data table again:

    Location Weight (N)
    Earth 553,3
    Rhea (a moon of Saturn) 15,0
    Saturn (a planet) 589,4
    Pluto (a dwarf planet) 35,1
    Mars (a planet) 209,7

    Use this table to calculate:

    1. Courtney's mass (m).
    2. The local acceleration due to gravity on Rhea (gRhea).
    3. The radius of Rhea (RRhea) if its mass is 2,317×1021 kg.
    INSTRUCTIONS:
    • Round all answers to two decimal places.
    • The radius of Rhea should be in scientific notation.
    • You must use these values for any physical constants required in your calculations.
    • You might find some of these physics formulas useful.
    Answer:
    1. m=
    2. gRhea=
    3. RRhea=
    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.abserror(0.01))
    one-of
    type(numeric.scientific.abserror(1e+03))
  3. Courtney uses the data from the table to produce a graph. What type of graph should Courtney use? Give a reason for your answer.

    Answer: Courtney should use a because the data is and make up a whole.


ID is: 3645 Seed is: 1271

True weight, apparent weight and weightlessness

Match the descriptions in the table below to the concepts of true weight, apparent weight, and weightlessness.

X A feeling experienced when the only force acting on the body is the gravitational force.
Y The force a body exerts on the surface it rests on.
Z The gravitational force the Earth (or any planet-like body) exerts on any object on or near its surface.
Answer:
  • True weight:
  • Apparent weight:
  • Weightlessness:

ID is: 3645 Seed is: 3318

True weight, apparent weight and weightlessness

Match the descriptions in the table below to the concepts of true weight, apparent weight, and weightlessness.

X The gravitational force the Earth (or any planet-like body) exerts on any object on or near its surface.
Y A feeling experienced when the only force acting on the body is the gravitational force.
Z The weight felt or perceived by a body.
Answer:
  • True weight:
  • Apparent weight:
  • Weightlessness:


ID is: 4605 Seed is: 4812

Explaining weightlessness

Adapted from DBE Nov 2016 Grade 11, P1, Q5
Physical constants · Physics formulas

Explain the term weightlessness.

Answer:

Weightlessness describes...


ID is: 4605 Seed is: 7318

Explaining weightlessness

Adapted from DBE Nov 2016 Grade 11, P1, Q5
Physical constants · Physics formulas

Explain the term weightlessness.

Answer:

Weightlessness describes...

15. Proportional reasoning with gravity



ID is: 3808 Seed is: 2095

Effect of mass and distance on the gravitational force

Two planets are gravitationally attracted to each other in deep space.

Consider a second scenario where, compared to the first scenario,

  • the distance between the two planets is greater,
  • and one mass is bigger while the other mass is smaller.

The above images are not perfectly to scale.

How will the gravitational force between the two planets in each scenario compare?

The gravitational force in the second scenario will be:

A stronger
B weaker
C the same
D impossible to know
Answer: The correct option is:

ID is: 3808 Seed is: 7041

Effect of mass and distance on the gravitational force

Two moons are gravitationally attracted to each other in deep space.

Consider a second scenario where, compared to the first scenario,

  • the distance between the two moons is greater,
  • and both masses are bigger.

The above images are not perfectly to scale.

How will the gravitational force between the two moons in each scenario compare?

The gravitational force in the second scenario will be:

A stronger
B weaker
C the same
D impossible to know
Answer: The correct option is:


ID is: 3321 Seed is: 9534

Multiple choice: Proportional reasoning and the gravitational force

Two asteroids (Y and Z) are in deep space. Y has mass m and Z has mass m. The distance between their centres of mass is d. The gravitational force experienced by asteroid Z is F.

Consider a different system of two asteroids in which:

  • the mass of the first asteroid is bigger than the mass of asteroid Y by a factor of 3,
  • the mass of the second asteroid is bigger than the mass of asteroid Z by a factor of 3,
  • and the distance between the two asteroids is 12d.

What is the magnitude of the gravitational force experienced between these two asteroids in terms of the original force F?

A 36F
B 94F
C 92F
D 18F
Answer:

The correct option is:


ID is: 3321 Seed is: 7568

Multiple choice: Proportional reasoning and the gravitational force

Two stars (Y and Z) are in deep space. Y has mass m and Z has mass 5m. The distance between their centres of mass is d. The gravitational force experienced by star Z is F.

Consider a different system of two stars in which:

  • the mass of the first star is the same as the mass of star Y,
  • the mass of the second star is the same as the mass of star Z,
  • and the distance between the two stars is 14d.

What is the magnitude of the gravitational force experienced between these two stars in terms of the original force F?

A 4F
B 116F
C 54F
D 16F
Answer:

The correct option is:



ID is: 1543 Seed is: 6961

Comparing masses of different planets

The weight of a rock lying on surface of Earth is FE. The radius of Earth is RE. On planet Epsilon, the same rock has weight 9FE. If the radius of planet Epsilon is three times that of Earth, and the mass of Earth is ME, then what is the mass of Epsilon in terms of ME?

INSTRUCTION: Round your answer to the nearest integer.
Answer: Mϵ = ME
numeric

ID is: 1543 Seed is: 9338

Comparing masses of different planets

The weight of a rock lying on surface of Earth is FE. The radius of Earth is RE. On planet Eta, the same rock has weight 6FE. If the radius of planet Eta is four times that of Earth, and the mass of Earth is ME, then what is the mass of Eta in terms of ME?

INSTRUCTION: Round your answer to the nearest integer.
Answer: Mη = ME
numeric


ID is: 4015 Seed is: 8375

Multiple choice: Weight and gravity on other planets

Adapted from WCED Metro Central Sep 2017 Grade 12, P1, Q1.2 & DBE Nov 2016 Grade 11 P1, Q1.4
Physical constants · Physics formulas

The gravitational acceleration on Earth is g. What would the gravitational acceleration be on Planet X with a third of the radius of Earth and three times the mass of the Earth?

A g
B 9g
C 13g
D 27g
Answer:

ID is: 4015 Seed is: 7637

Multiple choice: Weight and gravity on other planets

Adapted from WCED Metro Central Sep 2017 Grade 12, P1, Q1.2 & DBE Nov 2016 Grade 11 P1, Q1.4
Physical constants · Physics formulas

The weight of an astronaut on Earth is W. What would the weight of the astronaut be on Planet X with a third of the radius of Earth and a quarter of the mass of the Earth?

A 34W
B 112W
C 136W
D 94W
Answer:


ID is: 1492 Seed is: 6061

Comparing weights on different planets

A woman has a mass of 107 kg. Planet Gorgin is the same size as the Earth but has twice the mass of the Earth. What would the woman weigh on Gorgin, if the gravitational acceleration on Earth is 9,8 m·s2?

INSTRUCTION: Round your answer to one decimal place.
Answer: wG= N
one-of
type(numeric.abserror(0.1))

ID is: 1492 Seed is: 857

Comparing weights on different planets

A safe filled with diamonds has a mass of 241 kg. Planet Zaycore is the same size as the Earth but has three times the mass of the Earth. What would the safe weigh on Zaycore, if the gravitational acceleration on Earth is 9,8 m·s2?

INSTRUCTION: Round your answer to one decimal place.
Answer: wZ= N
one-of
type(numeric.abserror(0.1))


ID is: 1479 Seed is: 5259

Effect of mass on gravitational force

The International Space Station (ISS) has a mass M, as it orbits the Earth, it experiences a gravitational force of F. A space shuttle docks onto the ISS. The gravitational force the ISS experiences once the mass of the shuttle is added increases by a factor of 7.

What is the new combined mass of the ISS and the docked shuttle? Write your answer in terms of the original mass M of the ISS.

Answer: Mnew= M
numeric

ID is: 1479 Seed is: 581

Effect of mass on gravitational force

The International Space Station (ISS) has a mass M, as it orbits the Earth, it experiences a gravitational force of F. A space shuttle docks onto the ISS. The gravitational force the ISS experiences once the mass of the shuttle is added increases by a factor of 4.

What is the new combined mass of the ISS and the docked shuttle? Write your answer in terms of the original mass M of the ISS.

Answer: Mnew= M
numeric


ID is: 1541 Seed is: 3872

Effect of distance on gravitational force

A vulture is 9 km above the surface of the Earth. If its distance above the Earth is greatly increased, what happens to the mass of the vulture?

Answer:

The mass of the vulture would .


ID is: 1541 Seed is: 8979

Effect of distance on gravitational force

A vulture is 6 km above the surface of the Earth. If its distance above the Earth is greatly decreased, what happens to the mass of the vulture?

Answer:

The mass of the vulture would .



ID is: 3319 Seed is: 9450

Comparing gravitational forces

Two planets (V and W) are in deep space. V has mass m and W has mass 3m. The distance between their centres of mass is d. The gravitational force experienced by planet W is F.

Consider a different system of two planets in which:

  • the mass of the first planet is bigger than the mass of planet V by a factor of 3,
  • the mass of the second planet is bigger than the mass of planet W by a factor of 2,
  • and the distance between the two planets is d.

What is the magnitude of the gravitational force experienced between these two planets in terms of the original force F?

INSTRUCTION: Write your answer as a non-decimal fraction or as a whole number (whichever is more appropriate).
Answer:

Fnew= F

fraction

ID is: 3319 Seed is: 1187

Comparing gravitational forces

Two moons (V and W) are in deep space. V has mass m and W has mass m. The distance between their centres of mass is d. The gravitational force experienced by moon W is F.

Consider a different system of two moons in which:

  • the mass of the first moon is bigger than the mass of moon V by a factor of 2,
  • the mass of the second moon is bigger than the mass of moon W by a factor of 3,
  • and the distance between the two moons is 2d.

What is the magnitude of the gravitational force experienced between these two moons in terms of the original force F?

INSTRUCTION: Write your answer as a non-decimal fraction or as a whole number (whichever is more appropriate).
Answer:

Fnew= F

fraction


ID is: 3659 Seed is: 938

Proportional reasoning with Fg, m, and g

The relationship Fg=mg is an important equation in mechanics. It is the mathematical statement that shows the relationship between weight, mass, and a planet's local gravitational acceleration.

Consider two objects on the same planet (they have the same local gravitational acceleration).

  1. What can we say about the relationship between the weight of each object and the mass?

    Answer:

    The weight is the mass.

  2. Consider the options below and choose the one that represents the relationship between weight and mass symbolically:

    A Fgm
    B Fg<m
    C Fg>m
    D Fg1m
    E Fg=m
    Answer:

    The correct option is .

  3. The mass of the second object is 2 times bigger than the mass of the first object. How does the weight of the second object compare to the weight of the first object?

    Answer:

    The weight of the second object will be the weight of the first object.


ID is: 3659 Seed is: 9190

Proportional reasoning with Fg, m, and g

The relationship Fg=mg is an important equation in mechanics. It is the mathematical statement that shows the relationship between weight, mass, and a planet's local gravitational acceleration.

Consider two objects on the same planet (they have the same local gravitational acceleration).

  1. What can we say about the relationship between the weight of each object and the mass?

    Answer:

    The weight is the mass.

  2. Consider the options below and choose the one that represents the relationship between weight and mass symbolically:

    A Fg=m
    B Fg1m
    C Fgm
    D Fg<m
    E Fg>m
    Answer:

    The correct option is .

  3. The mass of the second object is 5 times smaller than the mass of the first object. How does the weight of the second object compare to the weight of the first object?

    Answer:

    The weight of the second object will be the weight of the first object.



ID is: 1480 Seed is: 1046

Effect of distance on gravitational force

A satellite experiences a gravitational force F when at the surface of the Earth.

What will the gravitational force on the satellite be if it orbits at a height (above the surface of the Earth) equal to the radius of the Earth?

INSTRUCTION: Write your answer as an exact fraction of F. Do not round off your answer.
Answer:

Forbit= F

numeric

ID is: 1480 Seed is: 5799

Effect of distance on gravitational force

A satellite experiences a gravitational force F when at the surface of the Earth.

What will the gravitational force on the satellite be if it orbits at a height (above the surface of the Earth) equal to twice the diameter of the Earth?

INSTRUCTION: Write your answer as an exact fraction of F. Do not round off your answer.
Answer:

Forbit= F

numeric


ID is: 1540 Seed is: 2980

Effect of mass on gravitational force

Two objects of mass 7x and 8x respectively exert a force F1 on each other when they are a distance D apart. What will the force be between two objects with masses 10x and 4x, also separated by the distance D, be?

INSTRUCTION: Write your answer as a fraction (or, where appropriate, as an integer).
Answer:

F2= F1

fraction

ID is: 1540 Seed is: 8293

Effect of mass on gravitational force

Two objects of mass 9x and 6x respectively exert a force F1 on each other when they are a distance D apart. What will the force be between two objects with masses 7x and 4x, also separated by the distance D, be?

INSTRUCTION: Write your answer as a fraction (or, where appropriate, as an integer).
Answer:

F2= F1

fraction


ID is: 1476 Seed is: 7595

Effect of gravitational force on distance

A satellite circles around the Earth at a certain height above the surface of the Earth. At this height the gravitational force is a factor 16 less than at the surface of the Earth.

If the Earth's radius is RE, calculate the height of the satellite above the surface of the Earth in terms of the radius of the Earth.

INSTRUCTION: Write your answer as a multiple of RE.
Answer: Rorbit= RE
numeric

ID is: 1476 Seed is: 7688

Effect of gravitational force on distance

A satellite circles around the Earth at a certain height above the surface of the Earth. At this height the gravitational force is a factor 9 less than at the surface of the Earth.

If the Earth's radius is RE, calculate the height of the satellite above the surface of the Earth in terms of the radius of the Earth.

INSTRUCTION: Write your answer as a multiple of RE.
Answer: Rorbit= RE
numeric


ID is: 1477 Seed is: 2668

Effect of mass on gravitational force

A satellite with mass MS orbits the Earth, and experiences a gravitational force of F. The satellite is hit by a meteoroid and part of the satellite breaks off. The new mass of the satellite is 13MS.

What will the new gravitational force on the satellite be?

INSTRUCTION: Write your answer as an exact fraction of the force F before the accident.
Answer: Fafter= F
numeric

ID is: 1477 Seed is: 6523

Effect of mass on gravitational force

A satellite with mass MS orbits the Earth, and experiences a gravitational force of F. The satellite is hit by a meteoroid and part of the satellite breaks off. The new mass of the satellite is 17MS.

What will the new gravitational force on the satellite be?

INSTRUCTION: Write your answer as an exact fraction of the force F before the accident.
Answer: Fafter= F
numeric

16. Chapter summary